CVE-2026-109206: LogicalDOC Community Edition through 9.3 Username Enumeration via AvatarServlet
LogicalDOC Community Edition through 9.3 contains a username enumeration vulnerability that allows unauthenticated attackers to identify valid accounts because the AvatarServlet (/avatar) performs no session validation. Attackers can supply usernames or numeric IDs in the userId parameter and compare 1x1 transparent images against real avatars to enumerate users and retrieve profile pictures.
Affected Software
Event History
Frequently Asked Questions
Who can exploit this issue?
Any unauthenticated remote attacker who can reach the LogicalDOC Community Edition AvatarServlet at /avatar can attempt enumeration. No account, privileges, or user interaction are required.
What information can an attacker obtain?
An attacker can test supplied usernames or numeric IDs in the userId parameter to determine whether accounts are valid. The endpoint can also expose profile pictures for users with real avatars.
Are default deployments affected?
Deployments running LogicalDOC Community Edition through 9.3 are affected if the /avatar endpoint is reachable. The described behavior occurs because AvatarServlet does not validate a session.
What can be done if an update cannot be applied immediately?
Restrict unauthenticated access to the /avatar endpoint, such as by requiring authentication at a reverse proxy or web server layer. This prevents anonymous requests from using the userId parameter to test accounts or retrieve avatars.