Auth bypass in Mycomplianceoffice Mco

CVE-2026-53905

MCO does not properly enforce authorization checks in the /customer/servlet/mco/webapi/admin-view-hierarchy/get-acl-tree-structure endpoint. An authenticated, low-privileged user can retrieve administrator access control structures without proper authorization checks. This may expose sensitive permission mappings and internal configuration details. Because vendor contact attempts were unsuccessful, the vulnerability has only been confirmed in version 25.3.3.1 but may also affect other versions.

Vulnerability class: Broken Access Control

EPSS: 0.002 (9.3th percentile) — read the EPSS interpretation.