foxcpp maddy up to 0.9.2 SMTP/IMAP /go-ldap/ldap/v3 strings.ReplaceAll ldap injection

Summaryinfo

A vulnerability marked as critical has been reported in foxcpp maddy up to 0.9.2. This issue affects the function strings.ReplaceAll of the file /go-ldap/ldap/v3 of the component SMTP/IMAP. This manipulation causes ldap injection. This vulnerability appears as CVE-2026-40193. The attack may be initiated remotely. There is no available exploit. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in foxcpp maddy up to 0.9.2. Affected by this vulnerability is the function strings.ReplaceAll of the file /go-ldap/ldap/v3 of the component SMTP/IMAP. The manipulation with an unknown input leads to a ldap injection vulnerability. The CWE definition for the vulnerability is CWE-90. The product constructs all or part of an LDAP query using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended LDAP query when it is sent to a downstream component. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-40193 since 04/09/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1505 according to MITRE ATT&CK.

Upgrading to version 0.9.3 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch 6a06337eb41fa87a35697366bcb71c3c962c44ba is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Vendor

• foxcpp

Name

• maddy

Version

• 0.9.0
• 0.9.1
• 0.9.2

License

• open-source

Website

• Product: https://github.com/foxcpp/maddy/

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