CVE-2026-27856

The record

Doveadm credentials are verified using direct comparison which is susceptible to timing oracle attack. An attacker can use this to determine the configured credentials. Figuring out the credential will lead into full access to the affected component. Limit access to the doveadm http service port, 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-2026-27858 Attacker can send a specifically crafted message before authentication that causes… Also affects dovecot24
• CVE-2026-27859 A mail message containing excessive amount of RFC 2231 MIME parameters causes LMTP to use… Also affects dovecot24