CVE-2025-43921: GNU Mailman

Medium severity, CVSS 5.3. EPSS: 0.5% chance of exploitation in the next 30 days.

GNU Mailman 2.1.39, as bundled in cPanel (and WHM), allows unauthenticated attackers to create lists via the /mailman/create endpoint. NOTE: multiple third parties report that they are unable to reproduce this, regardless of whether cPanel or WHM is used.

Affected products

• GNU Mailman: from 2.1.1, up to and including 2.1.39

Published 2025-04-20. Last modified 2026-06-17.