Improperly implemented security check for standard in PowerShell - CVE-2026-96303

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 Microsoft PowerShell when enforcing security restrictions. A remote attacker can exploit the security check over a network to bypass Windows Defender Application Control and PowerShell Constrained Language Mode restrictions.

Successful exploitation requires user interaction.

Affected software

How to mitigate CVE-2026-96303

External References

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2026-96303
• https://github.com/PowerShell/Announcements/blob/main/pwsh/2026/10/CVE-2026-96303.md

Related Security Bulletins

• Multiple vulnerabilities in PowerShell