========================================================================== Ubuntu Security Notice USN-4993-1 June 21, 2021 dovecot vulnerabilities ========================================================================== A security issue affects these releases of Ubuntu and its derivatives: - Ubuntu 21.04 - Ubuntu 20.10 - Ubuntu 20.04 LTS 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) 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. References: https://ubuntu.com/security/notices/USN-4993-1 CVE-2021-29157, CVE-2021-33515 Package Information: https://launchpad.net/ubuntu/+source/dovecot/1:2.3.13+dfsg1-1ubuntu1.1 https://launchpad.net/ubuntu/+source/dovecot/1:2.3.11.3+dfsg1-2ubuntu0.2 https://launchpad.net/ubuntu/+source/dovecot/1:2.3.7.2-1ubuntu3.4