Threat Intelligence / CVE / CVE-2026-21513
CVE-2026-21513
CISA KEVProtection mechanism failure in MSHTML Framework allows an unauthorized attacker to bypass a security feature over a network.
CVSS v3 vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weaknesses (CWE)
CWE-693
Threats tracking this CVE
- February 2026 Patch Tuesday: Six Zero-Days Among 59 CVEs — CRITICAL
- February 2026 Patch Tuesday: Six Zero-Days Among 59 CVEs — CrowdStrike-Discovered RDP EoP Exploited Since December 2025 — CRITICAL
- Microsoft MSHTML Remote Code Execution Zero-Day (CVE-2026-21513) — CRITICAL
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21513
- 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
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21513
Full detection coverage & IOCs for threats exploiting CVE-2026-21513 are available via the Threadlinqs MCP server (Purple tier). View plans →