CVE-2026-21509
Microsoft Office Security Feature Bypass Vulnerability
CVSS Score
7.8
EPSS Score
0.0%
EPSS Percentile
0th
Reliance on untrusted inputs in a security decision in Microsoft Office allows an unauthorized attacker to bypass a security feature locally.
| Vendor | microsoft |
| Product | microsoft 365 apps for enterprise |
| Ecosystems | |
| Industries | TechnologyEnterprise |
| Published | Jan 26, 2026 |
| Last Updated | Apr 1, 2026 |
⚠️ Actively Exploited — Act Now
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CVSS v3 Breakdown
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 Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality
Integrity
Availability
Affected Versions
Microsoft / Microsoft 365 Apps for Enterprise
16.0.1 < https://aka.ms/OfficeSecurityReleases
Microsoft / Microsoft Office 2016
16.0.0 < 16.0.5539.1001
Microsoft / Microsoft Office 2019
19.0.0 < 16.0.10417.20095
Microsoft / Microsoft Office LTSC 2021
16.0.1 < https://aka.ms/OfficeSecurityReleases
Microsoft / Microsoft Office LTSC 2024
16.0.0 < https://aka.ms/OfficeSecurityReleases
References
msrc.microsoft.com: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21509 cisa.gov: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21509 vicarius.io: https://www.vicarius.io/vsociety/posts/cve-2026-21509-detection-script-microsoft-office-security-feature-bypass-vulnerability vicarius.io: https://www.vicarius.io/vsociety/posts/cve-2026-21509-mitigation-script-microsoft-office-security-feature-bypass-vulnerability