Bug 2452176 (CVE-2026-27860)

Summary: CVE-2026-27860 dovecot: Dovecot: Authentication bypass and information disclosure via LDAP filter injection
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: low    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Dovecot. A remote attacker could exploit this vulnerability by injecting malicious Lightweight Directory Access Protocol (LDAP) filters during the authentication process. This is possible if the `auth_username_chars` configuration setting is empty. Successful exploitation could allow the attacker to bypass authentication restrictions and gain unauthorized access to information about the LDAP directory structure.
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Description OSIDB Bzimport 2026-03-27 09:02:13 UTC
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.