Actively exploited in the wild
Microsoft Office Security Feature Bypass Vulnerability
Microsoft - Office · Listed in the CISA KEV since 2026-01-26. This indicates confirmed attacks in production environments.
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.
CVE-2026-21509
HighCVSS 7.8KEVExploitation Probability (EPSS)
Very high risk99th percentile - higher than 99% of all known CVEs
Summary
Reliance on untrusted inputs in a security decision in Microsoft Office allows an unauthorized attacker to bypass a security feature locally.
Risk Assessment
The organization may be exposed to local attacks that could lead to unauthorized access to data or features in Microsoft Office.
Recommendation
It is recommended to review and strengthen input validation mechanisms in Microsoft Office applications and to regularly update the software.
Other vulnerabilities in Microsoft Office
See all- CVE-2026-42832High
Improper access control in Microsoft Office allows an unauthorized attacker to perform spoofing locally.
- CVE-2026-42831High
Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.
- CVE-2026-40419High
A use after free vulnerability in Microsoft Office allows an authorized attacker to locally elevate privileges.
- CVE-2026-40363High
Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.
- CVE-2026-26134High
Integer overflow or wraparound in Microsoft Office allows an authorized attacker to elevate privileges locally.
- CVE-2026-26110High
Microsoft Office has a vulnerability related to resource access using an incompatible type ('type confusion'), allowing an unauthorized attacker to execute code locally.
- CVE-2026-20953High
Use after free in Microsoft Office allows an unauthorized attacker to execute code locally.
- CVE-2026-20952High
Use after free in Microsoft Office allows an unauthorized attacker to execute code locally.
- CVE-2026-20943High
An untrusted search path vulnerability in Microsoft Office allows an unauthorized attacker to execute code locally.
- CVE-2025-62557High
A use after free vulnerability in Microsoft Office allows an unauthorized attacker to execute code locally.
Original NVD description (English source)
Reliance on untrusted inputs in a security decision in Microsoft Office allows an unauthorized attacker to bypass a security feature locally.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS