A security feature bypass exists when Device Guard does not properly validate certain elements of a signed PowerShell script. An attacker who successfully exploited this vulnerability could modify the contents of a PowerShell script without invalidating the signature associated with the file. Because Device Guard relies on the signature to determine the script is non-malicious, Device Guard could then allow a malicious script to execute. In an attack scenario, an attacker could modify the contents of a PowerShell script without invalidating the signature associated with the file. The update addresses the vulnerability by correcting how Device Guard validates certain elements of signed PowerShell scripts.