Bug 2458858 (CVE-2026-40193)

Summary: CVE-2026-40193 maddy: maddy: Identity spoofing and information disclosure via LDAP injection
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in maddy, a composable mail server. This LDAP (Lightweight Directory Access Protocol) injection vulnerability allows a remote attacker to inject arbitrary LDAP filter expressions into username fields during authentication. By exploiting this, an attacker can achieve identity spoofing, enabling them to authenticate as other users. Additionally, this flaw can lead to the enumeration of the LDAP directory and the blind extraction of sensitive LDAP attribute values.
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Description OSIDB Bzimport 2026-04-16 00:01:19 UTC 
maddy is a composable, all-in-one mail server. Versions prior to 0.9.3 contain an LDAP injection vulnerability in the auth.ldap module where user-supplied usernames are interpolated into LDAP search filters and DN strings via strings.ReplaceAll() without any LDAP filter escaping, despite the go-ldap/ldap/v3 library's ldap.EscapeFilter() function being available in the same import. This affects three code paths: the Lookup() filter, the AuthPlain() DN template, and the AuthPlain() filter. An attacker with network access to the SMTP submission or IMAP interface can inject arbitrary LDAP filter expressions through the username field in AUTH PLAIN or LOGIN commands. This enables identity spoofing by manipulating filter results to authenticate as another user, LDAP directory enumeration via wildcard filters, and blind extraction of LDAP attribute values using authentication responses as a boolean oracle or via timing side-channels between the two distinct failure paths. This issue has been fixed in version 0.9.3.