Home/CVE/Microsoft MSHTML Framework Protection Mechanism Failure Vulnerability
CVE

CVE-2026-21513

Microsoft MSHTML Framework Protection Mechanism Failure Vulnerability

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

HIGH · CVSS 8.8 ⚠ CISA KEV EPSS 0.2798
Act now
  • Listed on CISA KEV (known exploited in the wild)
  • SSVC exploitation status: active
  • EPSS ≥ 0.10 - elevated exploitation probability
  • EPSS percentile: top 3% of all CVEs by exploitation likelihood
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
⬢

Required Remediation

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

⬡

Weakness Classification

CWE-693Protection Mechanism Failure
▤

Affected Products & Versions

13
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 2012all versions
▣

Scoring & Timeline

8.8
HIGH · CVSS v3.1 · secure@microsoft.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD10 Feb 2026 · 06:16 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
SSVC triage · cisa-vulnrichment
Exploitation
active
Automatable
no
Technical impact
total
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

2
msrcCVE-2026-21513Security Feature Bypass
cisaKEV-CVE-2026-21513
🔗

References & Sources

3
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
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-frameworkMitigationThird Party Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21513US Government Resource
Intelligence Graph · click any node to traverse
CVETechnique ActorTool Family
drag to reposition · click any node to traverse · button top-right enlarges
External lookups - second-class, for what we don’t hold ourselves
NVDCVE.orgCISAVulnersExploit-DBGitHub PoCVulnCheck KEVGreyNoise
Vulnerabilities
CISA KEV catalog
CWE weaknesses
CAPEC attack patterns
Package vulnerabilities
Threat intelligence
Threat actors
Tools & malware
ATT&CK techniques
IOCs
Detection & defense
Sigma rules
YARA rules
Atomic Red Team tests
D3FEND countermeasures
Compliance
NIST 800-53
ISO 27001:2022
SOC 2 TSC
PCI-DSS v4.0
CIS Controls v8.1
About
All capabilities
Live statistics
Data sources
Privacy policy
Terms of service
threatengine.sh  ·  Open-source threat intelligence platform  ·  100+ authoritative sources  ·  Every fact traces to its origin