CVE-2022-30550

A vulnerability was found in the Dovecot IMAP Server. When two passdb configuration entries exist in the Dovecot configuration, which have the same driver and args settings, the incorrect username_filter and mechanism settings can be applied to passdb definitions. These incorrect settings can lead to an unintended security configuration and can permit privilege escalation with certain configurations involving a master user authentication. If the same passwd file or PAM is used for both normal and master users, an attacker could easily become a master user, potentially escalating privileges on the system.

Mitigation

Always authenticate master users from a different source than regular users, for example, use a separate passwd file. Alternatively, you can use global ACLs to ensure that only legitimate master users have privileged access.