{"id":"UBUNTU-CVE-2026-27856","details":"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.","modified":"2026-06-30T18:16:12.972775834Z","published":"2026-03-27T00:00:00Z","related":["USN-8136-1"],"upstream":["CVE-2026-27856"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-27856"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-27856"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8136-1"}],"affected":[{"package":{"name":"dovecot","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/dovecot?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1:2.3.4.1-5ubuntu3","1:2.3.7.2-1ubuntu1","1:2.3.7.2-1ubuntu2","1:2.3.7.2-1ubuntu3","1:2.3.7.2-1ubuntu3.1","1:2.3.7.2-1ubuntu3.2","1:2.3.7.2-1ubuntu3.3","1:2.3.7.2-1ubuntu3.4","1:2.3.7.2-1ubuntu3.5","1:2.3.7.2-1ubuntu3.6","1:2.3.7.2-1ubuntu3.7"],"ecosystem_specific":{"binaries":[{"binary_name":"dovecot-auth-lua","binary_version":"1:2.3.7.2-1ubuntu3.7"},{"binary_version":"1:2.3.7.2-1ubuntu3.7","binary_name":"dovecot-core"},{"binary_name":"dovecot-gssapi","binary_version":"1:2.3.7.2-1ubuntu3.7"},{"binary_name":"dovecot-imapd","binary_version":"1:2.3.7.2-1ubuntu3.7"},{"binary_name":"dovecot-ldap","binary_version":"1:2.3.7.2-1ubuntu3.7"},{"binary_version":"1:2.3.7.2-1ubuntu3.7","binary_name":"dovecot-lmtpd"},{"binary_name":"dovecot-lucene","binary_version":"1:2.3.7.2-1ubuntu3.7"},{"binary_name":"dovecot-managesieved","binary_version":"1:2.3.7.2-1ubuntu3.7"},{"binary_name":"dovecot-mysql","binary_version":"1:2.3.7.2-1ubuntu3.7"},{"binary_name":"dovecot-pgsql","binary_version":"1:2.3.7.2-1ubuntu3.7"},{"binary_name":"dovecot-pop3d","binary_version":"1:2.3.7.2-1ubuntu3.7"},{"binary_name":"dovecot-sieve","binary_version":"1:2.3.7.2-1ubuntu3.7"},{"binary_name":"dovecot-solr","binary_version":"1:2.3.7.2-1ubuntu3.7"},{"binary_name":"dovecot-sqlite","binary_version":"1:2.3.7.2-1ubuntu3.7"},{"binary_name":"dovecot-submissiond","binary_version":"1:2.3.7.2-1ubuntu3.7"},{"binary_name":"mail-stack-delivery","binary_version":"1:2.3.7.2-1ubuntu3.7"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-27856.json"}},{"package":{"name":"dovecot","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/dovecot?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1:2.3.16+dfsg1-3ubuntu2.7"}]}],"versions":["1:2.3.13+dfsg1-1ubuntu3","1:2.3.16+dfsg1-3ubuntu1","1:2.3.16+dfsg1-3ubuntu2","1:2.3.16+dfsg1-3ubuntu2.1","1:2.3.16+dfsg1-3ubuntu2.2","1:2.3.16+dfsg1-3ubuntu2.4","1:2.3.16+dfsg1-3ubuntu2.6"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_name":"dovecot-auth-lua","binary_version":"1:2.3.16+dfsg1-3ubuntu2.7"},{"binary_name":"dovecot-core","binary_version":"1:2.3.16+dfsg1-3ubuntu2.7"},{"binary_name":"dovecot-gssapi","binary_version":"1:2.3.16+dfsg1-3ubuntu2.7"},{"binary_name":"dovecot-imapd","binary_version":"1:2.3.16+dfsg1-3ubuntu2.7"},{"binary_version":"1:2.3.16+dfsg1-3ubuntu2.7","binary_name":"dovecot-ldap"},{"binary_name":"dovecot-lmtpd","binary_version":"1:2.3.16+dfsg1-3ubuntu2.7"},{"binary_version":"1:2.3.16+dfsg1-3ubuntu2.7","binary_name":"dovecot-lucene"},{"binary_name":"dovecot-managesieved","binary_version":"1:2.3.16+dfsg1-3ubuntu2.7"},{"binary_name":"dovecot-mysql","binary_version":"1:2.3.16+dfsg1-3ubuntu2.7"},{"binary_version":"1:2.3.16+dfsg1-3ubuntu2.7","binary_name":"dovecot-pgsql"},{"binary_name":"dovecot-pop3d","binary_version":"1:2.3.16+dfsg1-3ubuntu2.7"},{"binary_name":"dovecot-sieve","binary_version":"1:2.3.16+dfsg1-3ubuntu2.7"},{"binary_name":"dovecot-solr","binary_version":"1:2.3.16+dfsg1-3ubuntu2.7"},{"binary_version":"1:2.3.16+dfsg1-3ubuntu2.7","binary_name":"dovecot-sqlite"},{"binary_name":"dovecot-submissiond","binary_version":"1:2.3.16+dfsg1-3ubuntu2.7"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-27856.json"}},{"package":{"name":"dovecot","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/dovecot?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1:2.3.21+dfsg1-2ubuntu6.3"}]}],"versions":["1:2.3.20+dfsg1-1ubuntu3","1:2.3.21+dfsg1-2ubuntu1","1:2.3.21+dfsg1-2ubuntu2","1:2.3.21+dfsg1-2ubuntu4","1:2.3.21+dfsg1-2ubuntu5","1:2.3.21+dfsg1-2ubuntu6","1:2.3.21+dfsg1-2ubuntu6.1","1:2.3.21+dfsg1-2ubuntu6.2"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_name":"dovecot-auth-lua","binary_version":"1:2.3.21+dfsg1-2ubuntu6.3"},{"binary_version":"1:2.3.21+dfsg1-2ubuntu6.3","binary_name":"dovecot-core"},{"binary_name":"dovecot-gssapi","binary_version":"1:2.3.21+dfsg1-2ubuntu6.3"},{"binary_name":"dovecot-imapd","binary_version":"1:2.3.21+dfsg1-2ubuntu6.3"},{"binary_name":"dovecot-ldap","binary_version":"1:2.3.21+dfsg1-2ubuntu6.3"},{"binary_version":"1:2.3.21+dfsg1-2ubuntu6.3","binary_name":"dovecot-lmtpd"},{"binary_name":"dovecot-managesieved","binary_version":"1:2.3.21+dfsg1-2ubuntu6.3"},{"binary_version":"1:2.3.21+dfsg1-2ubuntu6.3","binary_name":"dovecot-mysql"},{"binary_name":"dovecot-pgsql","binary_version":"1:2.3.21+dfsg1-2ubuntu6.3"},{"binary_name":"dovecot-pop3d","binary_version":"1:2.3.21+dfsg1-2ubuntu6.3"},{"binary_version":"1:2.3.21+dfsg1-2ubuntu6.3","binary_name":"dovecot-sieve"},{"binary_version":"1:2.3.21+dfsg1-2ubuntu6.3","binary_name":"dovecot-solr"},{"binary_name":"dovecot-sqlite","binary_version":"1:2.3.21+dfsg1-2ubuntu6.3"},{"binary_name":"dovecot-submissiond","binary_version":"1:2.3.21+dfsg1-2ubuntu6.3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-27856.json"}},{"package":{"name":"dovecot","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/dovecot?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1:2.4.1+dfsg1-5ubuntu4.1"}]}],"versions":["1:2.3.21.1+dfsg1-1ubuntu2","1:2.4.1+dfsg1-5ubuntu1","1:2.4.1+dfsg1-5ubuntu3","1:2.4.1+dfsg1-5ubuntu4"],"ecosystem_specific":{"binaries":[{"binary_version":"1:2.4.1+dfsg1-5ubuntu4.1","binary_name":"dovecot-auth-lua"},{"binary_version":"1:2.4.1+dfsg1-5ubuntu4.1","binary_name":"dovecot-core"},{"binary_name":"dovecot-flatcurve","binary_version":"1:2.4.1+dfsg1-5ubuntu4.1"},{"binary_version":"1:2.4.1+dfsg1-5ubuntu4.1","binary_name":"dovecot-gssapi"},{"binary_version":"1:2.4.1+dfsg1-5ubuntu4.1","binary_name":"dovecot-imapd"},{"binary_version":"1:2.4.1+dfsg1-5ubuntu4.1","binary_name":"dovecot-ldap"},{"binary_name":"dovecot-lmtpd","binary_version":"1:2.4.1+dfsg1-5ubuntu4.1"},{"binary_name":"dovecot-managesieved","binary_version":"1:2.4.1+dfsg1-5ubuntu4.1"},{"binary_name":"dovecot-mysql","binary_version":"1:2.4.1+dfsg1-5ubuntu4.1"},{"binary_name":"dovecot-pgsql","binary_version":"1:2.4.1+dfsg1-5ubuntu4.1"},{"binary_name":"dovecot-pop3d","binary_version":"1:2.4.1+dfsg1-5ubuntu4.1"},{"binary_name":"dovecot-sieve","binary_version":"1:2.4.1+dfsg1-5ubuntu4.1"},{"binary_version":"1:2.4.1+dfsg1-5ubuntu4.1","binary_name":"dovecot-solr"},{"binary_name":"dovecot-sqlite","binary_version":"1:2.4.1+dfsg1-5ubuntu4.1"},{"binary_name":"dovecot-submissiond","binary_version":"1:2.4.1+dfsg1-5ubuntu4.1"}],"availability":"No subscription required"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-27856.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N"},{"type":"Ubuntu","score":"medium"}]}