It was discovered that Dovecot before versions 2.2.36.1 and 2.3.4.1 incorrectly handled client certificates. A remote attacker in possession of a valid certificate with an empty username field could possibly use this issue to impersonate other users.

A flaw was found in dovecot 2.0 up to 2.2.33 and 2.3.0. A abort of SASL authentication results in a memory leak in Dovecot auth client used by login processes. The leak has impact in high performance configuration where same login processes are reused and can cause the process to crash due to memory exhaustion.

Upstream patch:

https://github.com/dovecot/core/commit/1a29ed2f96da1be22fa5a4d96c7583aa81b8b060.patch

https://github.com/dovecot/core/commit/a9b135760aea6d1790d447d351c56b78889dac22.patch

In Dovecot before 2.2.36.3 and 2.3.x before 2.3.5.1, a local attacker can cause a buffer overflow in the indexer-worker process, which can be used to elevate to root. This occurs because of missing checks in the fts and pop3-uidl components.