USN-4993-1: Dovecot vulnerabilities

Releases

• Ubuntu 21.04
• Ubuntu 20.10
• Ubuntu 20.04 LTS

Packages

• dovecot - IMAP and POP3 email server

Details

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)

Update instructions

The problem can be corrected by updating your system to the following package versions:

Ubuntu 21.04

• dovecot-core - 1:2.3.13+dfsg1-1ubuntu1.1

Ubuntu 20.10

• dovecot-core - 1:2.3.11.3+dfsg1-2ubuntu0.2

Ubuntu 20.04

• dovecot-core - 1:2.3.7.2-1ubuntu3.4

In general, a standard system update will make all the necessary changes.

References

• CVE-2021-29157
• CVE-2021-33515