Kanboard 1.2.52 and prior contains a server-side request forgery vulnerability that allows authenticated users to bypass SSRF protections by supplying hexadecimal IP address notation in user-controlled URLs. Attackers can submit hexadecimal-encoded internal IP addresses through the web link creation feature, causing cURL to resolve and connect to internal network resources such as cloud instance metadata services, localhost services, and RFC1918 addresses while the isPrivateURL() filter in app/Core/Http/Client.php incorrectly treats the input as safe due to FILTER_VALIDATE_IP rejecting non-dotted-decimal notation.

Kanboard through 1.2.52, fixed in commit 564cc30, BoardAjaxController save() method (used by the kanban board drag-and-drop endpoint) validates the caller's role on the attacker-supplied project_id but never verifies that the supplied task_id actually belongs to that project. Because task identifiers are sequential integers shared across the entire instance, any authenticated user who is a member of at least one project can enumerate and move (corrupt/hide) tasks belonging to any other project on the same instance, including private projects they have no membership or role on.

Kanboard through 1.2.52, fixed in commit 928c68a, UserViewController::removeSession fails to validate the session id parameter before passing it to RememberMeSessionModel::remove, allowing authenticated users to delete other users' Remember Me sessions. Attackers can enumerate sequential session IDs and mass-invalidate persistent login sessions of any user, including administrators, forcing re-authentication and causing denial of service.