CVE detail
CVE-2026-21509: Microsoft Office Security Feature Bypass Vulnerability
Source: CISA Known Exploited Vulnerabilities catalog · back to feed
Vendor / product
Microsoft · Office
- Date added (KEV)
- Jan 26, 2026
- CISA due date
- Feb 16, 2026
- Ransomware campaign use
- Unknown
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.
Vendor fix: Vendor advisory
Scorifya interpretation
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Plain English
Technical detail
From CISA
Microsoft Office contains a security feature bypass vulnerability in which reliance on untrusted inputs in a security decision in Microsoft Office could allow an unauthorized attacker to bypass a security feature locally. Some of the impacted product(s) could be end-of-life (EoL) and/or end-of-service (EoS). Users are advised to discontinue use and/or transition to a supported version.
Please adhere to Microsoft’s recommended guidelines to address this vulnerability. Implement all final mitigations provided by the vendor for Office 2021, and apply the interim corresponding mitigations for Office 2016 and Office 2019 until the final patch becomes available. For more information please see: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21509 ; https://nvd.nist.gov/vuln/detail/CVE-2026-21509
See what attackers can see on your domain
This vulnerability is on CISA's Known Exploited Vulnerabilities list, so it is being exploited in the wild right now. Scorifya can't test for Microsoft directly, but in about 30 seconds it shows what your own domain exposes publicly across TLS, security headers, DNS, and cookies: the surface attackers probe first.
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See Scorifya Controls →References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21509Vendor Advisory
- https://www.vicarius.io/vsociety/posts/cve-2026-21509-mitigation-script-microsoft-office-security-feature-bypass-vulnerabilityMitigationThird Party Advisory
- https://www.vicarius.io/vsociety/posts/cve-2026-21509-detection-script-microsoft-office-security-feature-bypass-vulnerabilityThird Party Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21509US Government Resource
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