dovecot: If auth_username_chars is empty, it is possible to inject arbitrary LDAP filter to Dovecot's LDAP authentication
CVE-2026-27860 is fixed in 17 products on 1 platform, first by DEBIAN-CVE-2026-27860, released March 27, 2026. It is not reported as exploited. Patch Radar priority: Routine.
If auth_username_chars is empty, it is possible to inject arbitrary LDAP filter to Dovecot's LDAP authentication. This leads to potentially bypassing restrictions and allows probing of LDAP structure. Do not clear out auth_username_chars, or install fixed version. No publicly available exploits are known.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| dovecot · Debian 13.5 (trixie) | 1:2.4.1+dfsg1-6+deb13u4 | DEBIAN-CVE-2026-27860 | Mar 27, 2026 |
| dovecot · Debian 14 | 1:2.4.3+dfsg1-1 | DEBIAN-CVE-2026-27860 | Mar 27, 2026 |
| dovecot-auth-lua · Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | dovecot-auth-lua 1:2.4.1+dfsg1-5ubuntu4.1 | Apr 15, 2026 |
| dovecot-core · Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | dovecot-core 1:2.4.1+dfsg1-5ubuntu4.1 | Apr 15, 2026 |
| dovecot-flatcurve · Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | dovecot-flatcurve 1:2.4.1+dfsg1-5ubuntu4.1 | Apr 15, 2026 |
| dovecot-gssapi · Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | dovecot-gssapi 1:2.4.1+dfsg1-5ubuntu4.1 | Apr 15, 2026 |
| dovecot-imapd · Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | dovecot-imapd 1:2.4.1+dfsg1-5ubuntu4.1 | Apr 15, 2026 |
| dovecot-ldap · Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | dovecot-ldap 1:2.4.1+dfsg1-5ubuntu4.1 | Apr 15, 2026 |
| dovecot-lmtpd · Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | dovecot-lmtpd 1:2.4.1+dfsg1-5ubuntu4.1 | Apr 15, 2026 |
| dovecot-managesieved · Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | dovecot-managesieved 1:2.4.1+dfsg1-5ubuntu4.1 | Apr 15, 2026 |
| dovecot-mysql · Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | dovecot-mysql 1:2.4.1+dfsg1-5ubuntu4.1 | Apr 15, 2026 |
| dovecot-pgsql · Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | dovecot-pgsql 1:2.4.1+dfsg1-5ubuntu4.1 | Apr 15, 2026 |
| dovecot-pop3d · Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | dovecot-pop3d 1:2.4.1+dfsg1-5ubuntu4.1 | Apr 15, 2026 |
| dovecot-sieve · Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | dovecot-sieve 1:2.4.1+dfsg1-5ubuntu4.1 | Apr 15, 2026 |
| dovecot-solr · Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | dovecot-solr 1:2.4.1+dfsg1-5ubuntu4.1 | Apr 15, 2026 |
| dovecot-sqlite · Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | dovecot-sqlite 1:2.4.1+dfsg1-5ubuntu4.1 | Apr 15, 2026 |
| dovecot-submissiond · Ubuntu 25.10 (questing) | 1:2.4.1+dfsg1-5ubuntu4.1 | dovecot-submissiond 1:2.4.1+dfsg1-5ubuntu4.1 | Apr 15, 2026 |
| dovecot24 · opensuse-leap 16.0 | 2.4.3-160000.1.1 | OPENSUSE-SU-2026:20554-1 | Apr 16, 2026 |
| dovecot24 · sles 16.0 | 2.4.3-160000.1.1 | SUSE-SU-2026:21208-1 | Apr 16, 2026 |
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