CVE-2026-21509

7.8 HIGH CISA KEV - Actively Exploited
Published: January 26, 2026 Modified: February 11, 2026
View on NVD

Description

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

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21509
Source: secure@microsoft.com
Vendor Advisory
https://www.vicarius.io/vsociety/posts/cve-2026-21509-detection-script-microsoft-office-security-feature-bypass-vulnerability
Source: af854a3a-2127-422b-91ae-364da2661108
Third Party Advisory
https://www.vicarius.io/vsociety/posts/cve-2026-21509-mitigation-script-microsoft-office-security-feature-bypass-vulnerability
Source: af854a3a-2127-422b-91ae-364da2661108
Mitigation Third Party Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21509
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
US Government Resource

4 reference(s) from NVD

Quick Stats

CVSS v3 Score
7.8 / 10.0
EPSS (Exploit Probability)
9.3%
93th percentile
Exploitation Status
Actively Exploited
Remediation due: 2026-02-16

Weaknesses (CWE)

CWE-807

Affected Vendors

microsoft

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