CVE-2026-53909: medium-severity vulnerability in MyComplianceOffice MCO
Arbitrary File Upload in MCO
Published
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 5.3epss 0.4%
MCO does not correctly validate types of uploaded files. File upload validation functionality relies only on client-side checks, which can be bypassed. An authorized, low-privileged attacker can upload files with arbitrary types to the server.
Because vendor contact attempts were unsuccessful, the vulnerability has only been confirmed in version 25.3.3.1 but may also affect other versions.
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N
Affected products
MyComplianceOffice · MCORelated CVEs — MyComplianceOffice MCO
In the same product, most dangerous first.
CVE-2026-53906MEDIUMPath Disclosure and Path Traversal in MCOEPSS 0.5%CVE-2026-53903MEDIUMInsecure Direct Object Reference in MCOEPSS 0.4%CVE-2026-53908MEDIUMUser Enumeration in MCOEPSS 0.4%CVE-2026-53902HIGHPrivilege Escalation in MCOEPSS 0.3%CVE-2026-53904MEDIUMAccount Denial of Service in MCOEPSS 0.3%CVE-2026-53905MEDIUMUnauthorized Access to Administrator ACL View in MCOEPSS 0.3%