CVE-2026-21509
Microsoft Office Security Feature Bypass Vulnerability
⚠ KEVEPSS 12.1%
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.
How to fix CVE-2026-21509
No package mapping is available — consult the references below for vendor-specific guidance.
Is CVE-2026-21509 being exploited?
Yes — CVE-2026-21509 is on the CISA Known Exploited Vulnerabilities (KEV) catalog. Patch immediately.
Affected packages (0)
No package mapping in OSV.