CVE-2026-21509HIGH 7.8CISA KEVEPSS p99.4%
CVE-2026-21509Microsoft Office Security Feature Bypass Vulnerability
Microsoft / Office
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.
Scoring
| CVSS 3.1 | 7.8 (HIGH) |
| Vector | CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H |
| EPSS | 72.15% probability of exploitation · percentile 99.4% · 2026-06-18T12:00:27Z |
| Published | 2026-01-26 |
| Last modified | 2026-02-11 |
CISA KEV entry
Added to KEV: 2026-01-26
Underlying weaknesses· 1
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21509
- https://www.vicarius.io/vsociety/posts/cve-2026-21509-detection-script-microsoft-office-security-feature-bypass-vulnerability
- https://www.vicarius.io/vsociety/posts/cve-2026-21509-mitigation-script-microsoft-office-security-feature-bypass-vulnerability
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21509
1
| Type | Target | Confidence | Tier |
|---|---|---|---|
| Weakness | Reliance on Untrusted Inputs in a Security Decisioncwe-807 | 0% | live |
(incoming)1
| Type | Target | Confidence | Tier |
|---|---|---|---|
| KEVEntry | Microsoft Office Security Feature Bypass Vulnerabilitykev-cve-2026-21509 | 0% | live |
Related by meaning· 6
Nearest entities by semantic similarity across the cs-graph corpus.