Summaryinfo

A vulnerability was found in Open-Xchange OX Dovecot Pro up to 2.4.0/3.1.0 and classified as problematic. The affected element is an unknown function. Executing a manipulation of the argument auth_username_chars can lead to ldap injection. The identification of this vulnerability is CVE-2026-27860. The attack may be launched remotely. There is no exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic was found in Open-Xchange OX Dovecot Pro up to 2.4.0/3.1.0. This vulnerability affects an unknown code. The manipulation of the argument auth_username_chars 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. CVE summarizes:

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.

The advisory is available at documentation.open-xchange.com. This vulnerability was named CVE-2026-27860 since 02/24/2026. The exploitation appears to be difficult. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1505 by the MITRE ATT&CK project.

The vulnerability scanner Nessus provides a plugin with the ID 304092 (Linux Distros Unpatched Vulnerability : CVE-2026-27860), which helps to determine the existence of the flaw in a target environment.

Upgrading eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (304092) and CERT Bund (WID-SEC-2026-0891). Once again VulDB remains the best source for vulnerability data.

Affected

• Open Source Dovecot

Productinfo

Type

• Mail Server Software

Vendor

• Open-Xchange

Name

• OX Dovecot Pro

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4.0
• 3.0
• 3.1.0

License

• open-source

Website

• Vendor: https://www.open-xchange.com/

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