January 26, 2026 · Applied Cybernetics Group
CVE-2026-21509 — Microsoft Office
Microsoft Office Security Feature Bypass Vulnerability
- Added to KEV
2026-01-26- Federal due date
2026-02-16- Vendor
- Microsoft
- Product
- Office
- EPSS
- 99.4th percentile (score 0.722, as of
2026-07-13) - NVD CVSS v3.1
- 7.8 (HIGH)
- Ransomware use
- Unknown
- Upstream
- https://nvd.nist.gov/vuln/detail/CVE-2026-21509
CISA short description
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.
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.
NVD description
Reliance on untrusted inputs in a security decision in Microsoft Office allows an unauthorized attacker to bypass a security feature locally.