CVE-2021-40347: Check a user owns the email they are trying to unsubscribe (CVE-2021-40347) (3d880c56) · Commits · GNU Mailman / Postorius · GitLab

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.