CVE-2026-21509
high · 7.8Actively exploitedOn the CISA Known Exploited Vulnerabilities catalog
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Added 2026-01-26Remediation due 2026-02-16
Reliance on untrusted inputs in a security decision in Microsoft Office allows an unauthorized attacker to bypass a security feature locally.
7.8
CVSS
72.6%
EPSS (exploit prob.)
99th
EPSS percentile
2026-01-26
Published
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weaknesses
CWE-807
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| microsoft | 365_apps | all versions |
| microsoft | 365_apps | all versions |
| microsoft | office | 2016 |
| microsoft | office | 2016 |
| microsoft | office | 2019 |
| microsoft | office | 2019 |
| microsoft | office_long_term_servicing_channel | 2021 |
| microsoft | office_long_term_servicing_channel | 2021 |
| microsoft | office_long_term_servicing_channel | 2024 |
| microsoft | office_long_term_servicing_channel | 2024 |
Check a specific version with /api/v1/cve/match.
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
Query this programmatically:
curl https://evil-db.io/api/v1/cve/CVE-2026-21509