Actively exploited · Published Feb 10, 2026 · Assigned by microsoft
CVE-2026-21513MSHTML Framework Security Feature Bypass Vulnerability
High 8.8 Exploited
In plain English
A high-severity security flaw in Windows 10 Version 1607 from Microsoft. Attackers are actively exploiting it in the wild (listed by CISA on February 10, 2026). The chance it is exploited in the next 30 days is estimated at 15.9% (higher than 97% of all known vulnerabilities). Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
CISA guidance
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Federal agencies must remediate by Mar 3, 2026.
Official description
Protection mechanism failure in MSHTML Framework allows an unauthorized attacker to bypass a security feature over a network.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Windows 10 Version 1607 | 10.0.14393.0 – before 10.0.14393.8868 |
| Microsoft | Windows 10 Version 1809 | 10.0.17763.0 – before 10.0.17763.8389 |
| Microsoft | Windows 10 Version 21H2 | 10.0.19044.0 – before 10.0.19044.6937 |
| Microsoft | Windows 10 Version 22H2 | 10.0.19045.0 – before 10.0.19045.6937 |
| Microsoft | Windows 11 version 22H3 | 10.0.22631.0 – before 10.0.22631.6649 |
| Microsoft | Windows 11 Version 23H2 | 10.0.22631.0 – before 10.0.22631.6649 |
| Microsoft | Windows 11 Version 24H2 | 10.0.26100.0 – before 10.0.26100.7840 |
| Microsoft | Windows 11 Version 25H2 | 10.0.26200.0 – before 10.0.26200.7840 |
| Microsoft | Windows 11 version 26H1 | 10.0.28000.0 – before 10.0.28000.1575 |
| Microsoft | Windows 11 Version 26H1 | 10.0.28000.0 – before 10.0.28000.1575 |
| Microsoft | Windows Server 2012 | 6.2.9200.0 – before 6.2.9200.25923 |
| Microsoft | Windows Server 2012 (Server Core installation) | 6.2.9200.0 – before 6.2.9200.25923 |
| Microsoft | Windows Server 2012 R2 | 6.3.9600.0 – before 6.3.9600.23022 |
| Microsoft | Windows Server 2012 R2 (Server Core installation) | 6.3.9600.0 – before 6.3.9600.23022 |
| Microsoft | Windows Server 2016 | 10.0.14393.0 – before 10.0.14393.8868 |
| Microsoft | Windows Server 2016 (Server Core installation) | 10.0.14393.0 – before 10.0.14393.8868 |
| Microsoft | Windows Server 2019 | 10.0.17763.0 – before 10.0.17763.8389 |
| Microsoft | Windows Server 2019 (Server Core installation) | 10.0.17763.0 – before 10.0.17763.8389 |
| Microsoft | Windows Server 2022 | 10.0.20348.0 – before 10.0.20348.4773 |
| Microsoft | Windows Server 2022, 23H2 Edition (Server Core installation) | 10.0.25398.0 – before 10.0.25398.2149 |
| Microsoft | Windows Server 2025 | 10.0.26100.0 – before 10.0.26100.32370 |
| Microsoft | Windows Server 2025 (Server Core installation) | 10.0.26100.0 – before 10.0.26100.32370 |
Weakness: CWE-693 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
References
- MSHTML Framework Security Feature Bypass Vulnerability vendor-advisory, patch
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21513 government-resource
- https://www.vicarius.io/vsociety/posts/cve-2026-21513-detection-script-security-feature-bypass-vulnerability-in-mshtml-framework
- https://www.vicarius.io/vsociety/posts/cve-2026-21513-mitigation-script-security-feature-bypass-vulnerability-in-mshtml-framework