[USN-8136-2] Dovecot regression

========================================================================== Ubuntu Security Notice USN-8136-2 April 28, 2026 dovecot regression ========================================================================== A security issue affects these releases of Ubuntu and its derivatives: - Ubuntu 24.04 LTS - Ubuntu 22.04 LTS Summary: USN-8136-1 introduced a regression in Dovecot Software Description: - dovecot: IMAP and POP3 email server Details: USN-8136-1 fixed vulnerabilities in Dovecot. The update caused a regression on Ubuntu 22.04 LTS and Ubuntu 24.04 LTS. This update fixes the problem. We apologize for the inconvenience. Original advisory details: It was discovered that Dovecot incorrectly handled invalid base64 SASL data. An attacker could possibly use this issue to cause a denial of service. This issue only affected Ubuntu 25.10. (CVE-2025-59028) It was discovered that Dovecot script decode2text.sh incorrectly handled zip files. An attacker could possibly use this issue to obtain sensitive information. (CVE-2025-59031) It was discovered that Dovecot incorrectly handled certain AUTHENTICATE requests. An attacker could possibly use this issue to cause a denial of service. (CVE-2025-59032) It was discovered that Dovecot incorrectly handled certain SQL based authentication. An attacker could possibly use this issue to bypass authentication. This issue only affected Ubuntu 25.10. (CVE-2026-24031) It was discovered that Dovecot incorrectly handled certain LDAP based authentication. An attacker could possibly use this issue to bypass restrictions and allow probing of LDAP structure. This issue only affected Ubuntu 25.10. (CVE-2026-27860) It was discovered that Dovecot is vulnerable to replay attack under certain conditions. An attacker could possibly use this issue to bypass authentication. (CVE-2026-27855) It was discovered that Dovecot is vulnerable to a timing attack under certain conditions. An attacker could possibly use this issue to bypass authentication. (CVE-2026-27856) It was discovered that Dovecot incorrectly handled certain IMAP login requests. An attacker could possibly use this issue to cause a denial of service. (CVE-2026-27857) It was discovered that Dovecot incorrectly handled certain specially crafted messages. An attacker could possibly use this issue to cause a denial of service. (CVE-2026-27858) It was discovered that Dovecot incorrectly handled certain specially crafted mail messages. An attacker could possibly use this issue to cause a denial of service. (CVE-2026-27859) It was discovered that Dovecot incorrectly handles file paths. A attacker could possibly use this issue to perform a path traversal and obtain or modify arbitrary files. This issue only affected Ubuntu 22.04 LTS and Ubuntu 24.04 LTS. (CVE-2026-0394) Update instructions: The problem can be corrected by updating your system to the following package versions: Ubuntu 24.04 LTS dovecot-core 1:2.3.21+dfsg1-2ubuntu6.4 Ubuntu 22.04 LTS dovecot-core 1:2.3.16+dfsg1-3ubuntu2.8 In general, a standard system update will make all the necessary changes. References: https://ubuntu.com/security/notices/USN-8136-2 https://ubuntu.com/security/notices/USN-8136-1 CVE-2026-0394, https://launchpad.net/bugs/2150116 Package Information: https://launchpad.net/ubuntu/+source/dovecot/1:2.3.21+dfsg1-2ubuntu6.4 https://launchpad.net/ubuntu/+source/dovecot/1:2.3.16+dfsg1-3ubuntu2.8