USN-4993-1: Dovecot vulnerabilities
Kirin discovered that Dovecot incorrectly escaped kid and azp fields in JWT
tokens. A local attacker could possibly use this issue to validate tokens
using arbitrary keys. This issue only affected Ubuntu 20.10 and Ubuntu
21.04. (CVE-2021-29157)
Fabian Ising and Damian Poddebniak discovered that Dovecot incorrectly
handled STARTTLS when using the SMTP submission service. A remote attacker
could possibly use this issue to inject plaintext commands before
STARTTLS negotiation. (CVE-2021-33515)
Source: USN-4993-1: Dovecot vulnerabilities