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

Vulnerability Name

Microsoft 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.

Known To Be Used in Ransomware Campaigns?

Ransomware Status:

Unknown

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.

Additional Notes

• https://msrc.microsoft.com/update-guide/advisory/CVE-2026-21513
• https://nvd.nist.gov/vuln/detail/CVE-2026-21513

Related News Articles

• CISA orders feds to patch Windows flaw exploited as zero-dayApril 29, 2026
• CISA, Microsoft warn of active exploitation of Windows Shell vulnerability (CVE-2026-32202)April 29, 2026
• CISA Adds Actively Exploited ConnectWise and Windows Flaws to KEVApril 29, 2026
• Microsoft Confirms Active Exploitation of Windows Shell CVE-2026-32202April 28, 2026
• APT28 Deploys PRISMEX Malware in Campaign Targeting Ukraine and NATO AlliesApril 8, 2026

Related Weaknesses

• CWE-693