CVE-2026-21513
KEVMicrosoft MSHTML Framework Protection Mechanism Failure Vulnerability
Description
Microsoft MSHTML Framework contains a protection mechanism failure vulnerability that could allow an unauthorized attacker to bypass a security feature over a network.
Protection mechanism failure in MSHTML Framework allows an unauthorized attacker to bypass a security feature over a network.
CVSS 3.1 vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HPublishedFeb 10, 2026
Last modifiedJun 17, 2026
Added to KEVFeb 10, 2026
Remediation dueMar 3, 2026
References
- msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21513Vendor Advisory
- vicarius.io/vsociety/posts/cve-2026-21513-detection-script-security-feature-bypass-vulnerability-in-mshtml-frameworkThird Party Advisory
- vicarius.io/vsociety/posts/cve-2026-21513-mitigation-script-security-feature-bypass-vulnerability-in-mshtml-frameworkMitigationThird Party Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21513US Government Resource
0 recent articles mention this CVE
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Risk assessment · High
Actively exploited. Patch immediately.
- Exploitation
- Confirmed in the wild (CISA KEV)
- Federal remediation deadline
- Overdue by 237 days
- CVSS
- 8.8 HIGH
- EPSS (30-day exploit probability)
- 15.9% · top 3% of all CVEs
- Weakness
- CWE-693
- Attack vector
- Network, remotely reachable
Recommended actions
- 1.Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
- 2.Treat as emergency change: patch or isolate internet-facing instances first.
- 3.Review exposure: confirm which instances are reachable from the internet and restrict access until patched.
- 4.Hunt for compromise: review logs for the disclosure window, not just from the patch date.
Assessment is derived automatically from the live signals above; verify against your own asset inventory.