Steps to reproduce

1. Create the following useles but valid script in a directory containing an equal sign (=), e.g.
   c:\temp\=PSTest\Test.ps1

Enum State {
	Unknown = 1
	New = 2
}

2. Start the Script. You'll get:

The given assembly name or codebase was invalid. (Exception from HRESULT: 0x80131047)
…
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : OperationStopped: (:) [], FileLoadException
    + FullyQualifiedErrorId : System.IO.FileLoadException

Expected behavior

It's obvious: No valid character in the path of a PowerShell Script is allowed to affect the Script execution.

Actual behavior

PowerShell stops working with an exception because characters in the path of a PowerShell script can affect the PowerShell runtime.
I guess that a hacker is able to control powershell just by using special characters in the path of a script because PowerShell probably tries to interpret those characters.

Environment data

> $PSVersionTable
Name                           Value
----                           -----
PSVersion                      5.1.16299.98
PSEdition                      Desktop
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
BuildVersion                   10.0.16299.98
CLRVersion                     4.0.30319.42000
WSManStackVersion              3.0
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1