Microsoft has released new versions of PowerShell Core to fix a vulnerability that allows a local attacker to bypass Windows Defender Application Control (WDAC) enforcements. This could allow the attacker to execute untrusted programs even with WDAC enabled. To exploit the vulnerability, an attacker would first have access to the local machine where PowerShell is running in Constrained Language mode. The update addresses the vulnerability by correcting how the language mode functions in the system-wide application control solution is enabled in Windows.
Source: https://www.bleepingcomputer.com/news/microsoft/microsoft-patches-powershell-core-security-bug-to-fix-wdac-bypass/