CVE-2026-21509 HIGH

CVE-2026-21509: Microsoft Office Security Feature Bypass Vulnerability

Vendor Microsoft
Product Microsoft 365 Apps for Enterprise
Weakness CWE-807
KEV Status Known Exploited
Published January 26, 2026
Last update April 1, 2026
View on NVD All CVEs

CVSS base score

7.8/10
Attack vector Local
Attack complexity Low
Privileges required None
User interaction Required
Confidentiality High
Integrity High

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C

What the vulnerability does

01Description

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

CISA mandated remediation

02CISA Required Action

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Key dates

03Disclosure timeline

January 26, 2026 CVE published
April 1, 2026 Record updated