CVE-2026-27859

The record

A mail message containing excessive amount of RFC 2231 MIME parameters causes LMTP to use too much CPU. A suitably formatted mail message causes mail delivery process to consume large amounts of CPU time. Use MTA capabilities to limit RFC 2231 MIME parameters in mail messages, or upgrade to fixed version where the processing is limited. No publicly available exploits are known.

Affected packages

Related vulnerabilities

• CVE-2026-42006 An attacker can cause uncontrolled memory usage with excessive bracing over IMAP. Also affects dovecot24
• CVE-2026-40016 Attacker can upload a malicious Sieve script over ManageSieve service (or locally) to… Also affects dovecot24
• CVE-2026-40020 Attacker can use the IMAP SETACL command to inject the anyone permission to user's… Also affects dovecot24
• CVE-2026-33603 Attacker can use a specially crafted base64 exchange between Dovecot and Client to fake… Also affects dovecot24
• CVE-2026-27851 When safe filter is used with variable expansion, all following pipelines on the same… Also affects dovecot24
• CVE-2026-27860 If auth_username_chars is empty, it is possible to inject arbitrary LDAP filter to… Also affects dovecot24
• CVE-2026-27858 Attacker can send a specifically crafted message before authentication that causes… Also affects dovecot24
• CVE-2026-24031 Dovecot SQL based authentication can be bypassed when auth_username_chars is cleared by… Also affects dovecot24