CVE-2026-21513

Name: CVE-2026-21513
Creator: NVD / NIST
Published: 2026-02-10T18:16:33.643+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.8/10Actively ExploitedEPSS 15.38%

Last modified Jun 17, 2026

CVE-2026-21513 is a high-severity vulnerability rated 8.8/10 on the CVSS scale. Protection mechanism failure in MSHTML Framework allows an unauthorized attacker to bypass a security feature over a network.. CISA has confirmed active exploitation in the wild. EPSS estimates a 15.38% chance of exploitation in the next 30 days.

Description

Protection mechanism failure in MSHTML Framework allows an unauthorized attacker to bypass a security feature over a network.

Metrics

CVSS 3.1

8.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

EPSS Probability

15.38%

96.4th percentile

Probability of exploitation in the next 30 days. Learn more

Exploitation Status

This vulnerability is listed in CISA’s Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. Federal agencies must remediate by Mar 3, 2026.

Weakness Enumeration

CWE-693

Affected Software

Vendor	Product	Versions
Microsoft	Windows 10 1607	< 10.0.14393.8868
Microsoft	Windows 10 1809	< 10.0.17763.8389
Microsoft	Windows 10 21h2	< 10.0.19044.6937
Microsoft	Windows 10 22h2	< 10.0.19045.6937
Microsoft	Windows 11 23h2	< 10.0.22631.6649
Microsoft	Windows 11 24h2	< 10.0.26100.7781
Microsoft	Windows 11 25h2	< 10.0.26200.7781
Microsoft	Windows Server 2012	All versions
Microsoft	Windows Server 2012	r2
Microsoft	Windows Server 2016	< 10.0.14393.8868
Microsoft	Windows Server 2019	< 10.0.17763.8389
Microsoft	Windows Server 2022	< 10.0.20348.4711
Microsoft	Windows Server 2022 23h2	< 10.0.25398.2149
Microsoft	Windows Server 2025	< 10.0.26100.32313

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21513Vendor Advisory
https://www.vicarius.io/vsociety/posts/cve-2026-21513-detection-script-security-feature-bypass-vulnerability-in-mshtml-frameworkThird Party Advisory
https://www.vicarius.io/vsociety/posts/cve-2026-21513-mitigation-script-security-feature-bypass-vulnerability-in-mshtml-frameworkMitigation, Third Party Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21513US Government Resource

Timeline

Published: Feb 10, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-21513?

Protection mechanism failure in MSHTML Framework allows an unauthorized attacker to bypass a security feature over a network.

How severe is CVE-2026-21513?

CVE-2026-21513 has a CVSS score of 8.8/10 (HIGH severity). The EPSS model estimates a 15.38% probability of exploitation in the next 30 days. This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog.

How do I fix CVE-2026-21513?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-21513?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST