CVE-2026-34828: listmonk's active sessions remain valid after password reset and password change

A session management vulnerability allows previously issued authenticated sessions to remain valid after sensitive account security changes, specifically password reset and password change. As a result, an attacker who has already obtained a valid session cookie can retain access to the account even after the victim changes or resets their password.

This weakens account recovery and session security guarantees. I reproduced the issue on listmonk v6.0.0.