CVE-2026-21509
Microsoft Office Security Feature Bypass Vulnerability
- State
- Published
- Severity
- 7.8 High
- Published
- Jan 26, 2026
- Updated
- Jul 30, 2026
- Reserved
- Dec 30, 2025
Description
Reliance on untrusted inputs in a security decision in Microsoft Office allows an unauthorized attacker to bypass a security feature locally.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 7.8 High | 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 | microsoft |
Weaknesses
- CWE-807 Reliance on Untrusted Inputs in a Security Decision
Affected Products
| Product | Versions |
|---|---|
Microsoft 365 Apps for EnterpriseMicrosoft |
|
Microsoft Office 2016Microsoft |
|
Microsoft Office 2019Microsoft |
|
Microsoft Office LTSC 2021Microsoft |
|
Microsoft Office LTSC 2024Microsoft |
|
References
- Microsoft Office Security Feature Bypass Vulnerabilityvendor-advisorypatch
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21509government-resource
- https://www.vicarius.io/vsociety/posts/cve-2026-21509-detection-script-microsoft-office-security-feature-bypass-vulnerability
- https://www.vicarius.io/vsociety/posts/cve-2026-21509-mitigation-script-microsoft-office-security-feature-bypass-vulnerability
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