Microsoft Office: Microsoft Office Security Feature Bypass Vulnerability
› Microsoft Office
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- started
- Jan 26, 2026
- closed
- Jan 26, 2026
- CVEs
- 1
- sources
- 3
## summary
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. Added to CISA KEV on 2026-01-26.
severity: Actively exploited (CISA KEV)
## cve ids[1]
## affected
- See vendor advisory / CISA notes (versions not always listed in KEV feed)
## fixed in
- See vendor advisory linked in sources
## timeline[1]
CISA added CVE-2026-21509 to the KEV catalog (due 2026-02-16).
## advisories[3]
## notes & caveats
Derived from CISA KEV JSON feed catalogVersion 2026.10.21. Exact affected/fixed version strings are not always in the KEV record — verify against the vendor advisory URL. startedAt uses dateAdded (exploitation may have begun earlier).
