CVE-2026-53904 Account Denial of Service in MCO
Attackers can lock victims out of MCO accounts by repeatedly triggering password resets, causing account denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-53904?
CVE-2026-53904 is a medium-severity denial of service vulnerability in MyComplianceOffice MCO, published on 1 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2026-53904?
It affects 1 product.
Products include Mycomplianceoffice Mco.
How do I fix CVE-2026-53904?
No fix has been published for CVE-2026-53904 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-53904 being exploited?
There is no known exploitation of CVE-2026-53904 in the wild and no public exploit code.
Sources
Also known as GHSA-4p9c-w7qw-q5pq.