Improperly implemented security check for standard in Microsoft Windows and Windows Server - CVE-2026-85805

Vulnerability details

The vulnerability allows a remote attacker to bypass Windows Defender Application Control and PowerShell Constrained Language Mode restrictions.

The vulnerability exists due to an improperly implemented security check for a standard in Windows PowerShell when enforcing restrictions on untrusted code. A remote attacker can exploit the security check over a network to bypass these restrictions and run untrusted code with capabilities those protections are designed to block.

User interaction is required.

Affected software

How to mitigate CVE-2026-85805

External References

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2026-85805
• https://support.microsoft.com/help/5127648

Related Security Bulletins

• Multiple vulnerabilities in Microsoft Windows