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
EPSS Score
72.2%
Exploitation probability in 30 days
Top 1% most likely to be exploited
Attack Characteristics
Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Confidentiality
High
Integrity
High
Availability
High
Published: January 26, 2026 (165 days ago)
Last Modified: June 25, 2026
Vendor: Microsoft
Source: NVD
⚠️ CISA Known Exploited Vulnerability
Added to KEV: 2026-01-26
Remediation Due: 2026-02-16 (⚠ 145d overdue)
Vulnerability Report
Generated by CyberWatcher
Description
Reliance on untrusted inputs in a security decision in Microsoft Office allows an unauthorized attacker to bypass a security feature locally.
CWE
CWE-807Affected Products
microsoft 365 appsmicrosoft officemicrosoft office long term servicing channel