New Windows Flaw Lets Attackers Bypass Mark of the Web

Microsoft released a security update for CVE-2026-20824, a Windows Remote Assistance vulnerability that can bypass Mark of the Web (MOTW) protections and allow quieter execution of file-based payloads after user interaction; exploitation typically requires a user to open a malicious file delivered via phishing, collaboration tools, or compromised sites. The advisory notes a CVSS of 5.5, the vendor patch is available, and recommended mitigations include prompt patching, tightening email/web controls, enforcing endpoint protections (SmartScreen, ASR, Protected View), applying application control (WDAC/AppLocker), restricting Remote Assistance, and improving detection and incident response.