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
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N.
EPSS exploit prediction
EPSS: 0.003 (22.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 22nd percentile — 22.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000
Affected products
- Mycomplianceoffice Mco — versions 25.3.3.1
- Mycomplianceoffice — versions 25.3.3.1
Weakness classification (CWE)
References
- cert.pl/en/posts/2026/07/CVE-2026-53902 (Third Party Advisory, third-party-advisory)
- mco.mycomplianceoffice.com/ (Product, product)
Frequently asked questions
- What is CVE-2026-53905?
- CVE-2026-53905 is a high-severity vulnerability in Mycomplianceoffice Mco, classified under Incorrect Authorization. CVSS score: 7.1/10. Published 2026-07-01.
- How severe is CVE-2026-53905?
- High severity. CVSS v3 base score is 7.1 out of 10.