CVE-2026-53909

Summary

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.

Affected Software

VendorProductVersion RangeStatus
MyComplianceOfficeMCO25.3.3.1affected

Weaknesses

  • CWE-434: CWE-434 Unrestricted Upload of File with Dangerous Type

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References