# CVE-2026-21509: A Microsoft Office bug is being used in attacks

Status: Being used now (CISA KEV, added 2026-01-26)
Who: 
Do this: 

## Agent prompt (read-only)
Read-only check, change nothing, send nothing anywhere.
Is Microsoft Office (CVE-2026-21509) installed or running on this machine or in this project?
1. Find every copy and its version (apps, packages, containers, lockfiles).
2. Compare each version against the vendor's fixed version for CVE-2026-21509. Quote the vendor page you used.
3. Report a table: where, version, fixed version, status (exposed / fixed / not installed / unsure).
4. List the exact update steps, but do not run them.

## Official 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.

## Sources
- https://nvd.nist.gov/vuln/detail/CVE-2026-21509
- https://nvd.nist.gov/vuln/detail/CVE-2026-21509

Generated by isitexploited.org from public sources. Verify version numbers against the vendor before acting.