CVE-2026-27858

The record

Attacker can send a specifically crafted message before authentication that causes managesieve to allocate large amount of memory. Attacker can force managesieve-login to be unavailable by repeatedly crashing the process. Protect access to managesieve protocol, or install fixed version. 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-2026-27859 A mail message containing excessive amount of RFC 2231 MIME parameters causes LMTP to use… Also affects dovecot24
• CVE-2026-24031 Dovecot SQL based authentication can be bypassed when auth_username_chars is cleared by… Also affects dovecot24