VULNERABILITY INTELLIGENCE

CVE-2026-53909

CVSS score6.5 MEDIUM
EPSS probability0.39%
CISA KEVNot currently listed
Published2026-07-01
Last modified2026-10-25
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

Description

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.

Weakness classification

  • cvd@cert.pl: CWE-434

Primary references