CVE-2025-41066: Horde Groupware

Medium severity, CVSS 5.3. EPSS: 0.2% chance of exploitation in the next 30 days.

Horde Groupware v5.2.22 has a user enumeration vulnerability that allows an unauthenticated attacker to determine the existence of valid accounts on the system. To exploit the vulnerability, an HTTP request must be sent to ‘/imp/attachment.php’ including the parameters ‘id’ and ‘u’. If the specified user exists, the server will return the download of an empty file; if it does not exist, no download will be initiated, which unequivocally reveals the validity of the user.

Affected products

• Horde Groupware: version 5.2.22 only

Published 2025-12-02. Last modified 2026-06-17.