CVE-2026-21509

high Microsoft ⚠️ CISA KEV — Exploited in the Wild
CVSS v3 Base Score
7.8
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Published: January 26, 2026
Last Modified: February 11, 2026
Vendor: Microsoft

⚠️ CISA Known Exploited Vulnerability

Added to KEV: 2026-01-26
Remediation Due: 2026-02-16

Description

Reliance on untrusted inputs in a security decision in Microsoft Office allows an unauthorized attacker to bypass a security feature locally.

CWE

CWE-807

Affected Products

microsoft 365 appsmicrosoft officemicrosoft office long term servicing channel

References