CVE-2026-21513: Microsoft MSHTML Framework Protection Mechanism Failure Vulnerability

Added to the CISA Known Exploited Vulnerabilities catalog on 10 Feb 2026. Vendor: Microsoft. Product: Windows.

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

Required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. (due 03 Mar 2026)