Vulnerability · Published Jul 1, 2026 · Assigned by CERT-PL
CVE-2026-53908User Enumeration in MCO
Medium 6.9
In plain English
A medium-severity security flaw in MCO from MyComplianceOffice. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 30% of all known vulnerabilities).
Official description
MCO is vulnerable to User Enumeration through authentication-related functionalities. The application returns distinguishable responses for valid and invalid users during username reminder and password reset operations. An attacker can leverage these differences to enumerate valid usernames and email addresses. Because vendor contact attempts were unsuccessful, the vulnerability has only been confirmed in version 25.3.3.1 but may also affect other versions.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| MyComplianceOffice | MCO | 25.3.3.1 |
Weakness: CWE-204 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
References
- https://cert.pl/en/posts/2026/07/CVE-2026-53902 third-party-advisory
- https://mco.mycomplianceoffice.com/ product