Vulnerability in Mycomplianceoffice Mco
CVE-2026-53904
MCO is vulnerable to Account Denial of Service due to improper implementation of password reset functionality. Each password reset request invalidates previously set password as well as previously issued temporary passwords, furthermore, password resets are not limited in any way. An attacker who provides victim's email and answer to their security question, can successfully initiate the reset process and continuously invalidate credentials, effectively locking the victim out of their account. Answering security questions has a limited number of tries which lowers the risk of this vulnerability. Because vendor contact attempts were unsuccessful, the vulnerability has only been confirmed in version 25.3.3.1 but may also affect other versions.
EPSS: 0.002 (10.6th percentile) — read the EPSS interpretation.
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:N/A:H.
Affected products
- Mycomplianceoffice Mco — versions 25.3.3.1
Weakness classification (CWE)
References
- cvd@cert.pl (Third Party Advisory, third-party-advisory)
- cvd@cert.pl (Product, product)
Frequently asked questions
- What is CVE-2026-53904?
- CVE-2026-53904 is a high-severity vulnerability in Mycomplianceoffice Mco, classified under Improper Restriction of Excessive Authentication Attempts. CVSS score: 7.1/10. Published 2026-07-01.
- How severe is CVE-2026-53904?
- High severity. CVSS v3 base score is 7.1 out of 10.