Is CVE-2026-21513 in the CISA KEV catalog?

Yes. CVE-2026-21513 is on the CISA Known Exploited Vulnerabilities list, added 2026-02-10.

What is the CVSS severity of CVE-2026-21513?

CVE-2026-21513 has a CVSS v3 base score of 8.8 (Important).

What is the EPSS score for CVE-2026-21513?

CVE-2026-21513 has an EPSS score of 15.38% (96th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-21513?

Install KB5075999 for Windows 10 Version 1607. Fixes are available for 22 affected products.

CVE & CISA-KEV Catalog

CVE-2026-21513

HIGHCISA KEVEPSS 96th pctl

8.8

CVSS v3

NVD

Description

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

CWE-693Protection Mechanism Failure

How to fix

Remediation Available

Windows 10 Version 1607Windows

Install:KB5075999Microsoft

Windows 10 Version 1809Windows

Install:KB5075904Microsoft

Windows 10 Version 21H2Windows

Install:KB5075912Microsoft

Windows 10 Version 22H2Windows

Install:KB5075912Microsoft

Windows 11 Version 23H2Windows

Install:KB5075941Microsoft

Windows 11 Version 24H2Windows

Install:KB5077181Microsoft

Install:KB5077212Microsoft

Windows 11 Version 25H2Windows

Install:KB5077212Microsoft

Install:KB5077181Microsoft

Windows 11 Version 26H1Windows

Install:KB5077179Microsoft

Windows 11 version 26H1Windows

Install:KB5077179Microsoft

Windows Server 2012Windows

Install:KB5075971Microsoft

Windows Server 2012 (Server Core installation)Windows

Install:KB5075971Microsoft

Windows Server 2012 R2Windows

Install:KB5075970Microsoft

Windows Server 2012 R2 (Server Core installation)Windows

Install:KB5075970Microsoft

Windows Server 2016Windows

Install:KB5075999Microsoft

Windows Server 2016 (Server Core installation)Windows

Install:KB5075999Microsoft

Windows Server 2019Windows

Install:KB5075904Microsoft

Windows Server 2019 (Server Core installation)Windows

Install:KB5075904Microsoft

Windows Server 2022Windows

Install:KB5075906Microsoft

Install:KB5075943Microsoft

Windows Server 2022 (Server Core installation)Windows

Install:KB5075906Microsoft

Install:KB5075943Microsoft

Windows Server 2022, 23H2 Edition (Server Core installation)Windows

Install:KB5075897Microsoft

Windows Server 2025Windows

Install:KB5075942Microsoft

Install:KB5075899Microsoft

Windows Server 2025 (Server Core installation)Windows

Install:KB5075942Microsoft

Install:KB5075899Microsoft

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Exploit Intelligence

15.38%probability of exploitation in 30 days

96thpercentile

Very high risk: more likely to be exploited than 96% of all known CVEs.

Known Exploited Vulnerability (CISA KEV)

Microsoft MSHTML Framework Protection Mechanism Failure Vulnerability

Microsoft MSHTML Framework contains a protection mechanism failure vulnerability that could allow an unauthorized attacker to bypass a security feature over a network.

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Remediation due: 2026-03-03

References

Vendor Advisory1

msrc.microsoft.com

Mitigation1

vicarius.io

Third-Party Advisory1

vicarius.io

Government Resource1

cisa.gov

Related Vulnerabilities

Other CWE-693 (Protection Mechanism Failure) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2013-2465	Critical	9.8	99%	KEV + Ransom	-
CVE-2024-21412	High	8.1	95%	KEV + Ransom	Fix
CVE-2013-0431	Medium	5.3	90%	KEV + Ransom	-
CVE-2025-40536	High	8.1	82%	KEV	Fix
CVE-2019-1003030	Critical	9.9	76%	KEV	-
CVE-2025-0411	High	7.0	67%	KEV	Fix

Embed a live status badge for CVE-2026-21513

Markdown

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-03-30.