CVE-2021-40347: Postorius Project Postorius

Medium severity, CVSS 5.4. EPSS: 1.2% chance of exploitation in the next 30 days.

An issue was discovered in views/list.py in GNU Mailman Postorius before 1.3.5. An attacker (logged into any account) can send a crafted POST request to unsubscribe any user from a mailing list, also revealing whether that address was subscribed in the first place.

Affected products

• Postorius Project Postorius: before 1.3.5 (fixed in 1.3.5)

Published 2021-09-10. Last modified 2026-06-17.