A security feature bypass vulnerability exists in Windows Defender Application Control (WDAC) which could allow an attacker to bypass WDAC enforcement, aka 'Windows Defender Application Control Security Feature Bypass Vulnerability'.

Affected: NuGet: System.Management.Automation

## Microsoft Security Advisory CVE-2019-1167: Windows Defender Application Control Security Feature Bypass Vulnerability

# Microsoft Security Advisory CVE-2019-1167: Windows Defender Application Control Security Feature Bypass Vulnerability

## Executive Summary

A security feature bypass vulnerability exists in Windows Defender Application Control (WDAC) which could allow an attacker to bypass WDAC enforcement. An attacker who successfully exploited this vulnerability could circumvent PowerShell Core Constrained Language Mode on the machine.

To exploit the vulnerability, an attacker would first have access to the local machine where PowerShell is running in Constrained Language mode. By doing that an attacker could leverage script debugging to abuse signed modules in an unintended way.

The update addresses the vulnerability by correcting how PowerShell functions in Constrained Language Mode. System administrators are advised to update PowerShell Core to an unaffected version (see [affected software](#user-content-affected-software).)

## Discussion

Please use PowerShell/PowerShell#TBD for discussion of this advisory.

## <a name="affected-software">Affected Software</a>

The vulnerability affects PowerShell Core prior to the following versions:

| PowerShell Core Version | Fixed in | |-------------------------|-------------------| | 6.1 | 6.1.5 | | 6.2 | 6.2.2 |

## Advisory FAQ

### How do I…