Microsoft Office Security Feature Bypass Vulnerability

Description

References

• msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21509 · Vendor Advisory
• vicarius.io/vsociety/posts/cve-2026-21509-detection-script-microsoft-office-security-feature-bypass-vulnerability · Third Party Advisory
• vicarius.io/vsociety/posts/cve-2026-21509-mitigation-script-microsoft-office-security-feature-bypass-vulnerability · Mitigation
• cisa.gov/known-exploited-vulnerabilities-catalog · US Government Resource
• CISA KEV · CVE-2026-21509

More vulnerabilities in office

• CVE-2026-70105HIGH 7.5Improper input validation in Microsoft Office Word allows an unauthorized attacker to disclose information over a network.
• CVE-2026-55054MEDIUM 6.5Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information over a network.
• CVE-2026-47293HIGH 7.0Use after free in Microsoft Office Click-To-Run allows an authorized attacker to elevate privileges locally.
• CVE-2026-42832MEDIUM 5.5Improper access control in Microsoft Office allows an unauthorized attacker to perform spoofing locally.
• CVE-2026-42831HIGH 7.8Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.