Ubuntu 21.04, 20.10: USN-4993-1 Moderate: Dovecot Security Issues

ubuntu

June 21, 2021

Several security issues were fixed in Dovecot.

Summary

Several security issues were fixed in Dovecot.

Software Description:

- 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)

Topics Covered

security advisory Ubuntu dovecot email server issue resolution

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 LTS:
  dovecot-core                    1:2.3.7.2-1ubuntu3.4

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