CVE-2026-76073 is an authorization bypass vulnerability in HumanSignal's Label Studio affecting versions up to 1.23.0. The AnnotationAPI endpoint in label_studio/tasks/api.py uses a queryset that retrieves all annotations without scoping them to the requesting user's organization. Permissions are checked only for authentication, not for organization membership, enabling any logged-in user to enumerate annotation IDs and access or modify annotations from other organizations. This flaw is due to the lack of a get_queryset override to enforce organization-based filtering, unlike the sibling task endpoint which correctly restricts access by project organization. The same issue exists in AnnotationConvertAPI in the same file.

Authenticated users can bypass intended access controls to read, modify, or delete annotations belonging to other organizations on the same Label Studio instance. This leads to unauthorized data exposure and potential data integrity violations across organizational boundaries.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict access to the Label Studio instance to trusted users only and monitor for suspicious activity. Consider implementing custom access controls or request the vendor for a patch that scopes annotation queries to the user's organization.