Notepad++: Install-time PowerShell command injection through installation path

Notepad++ is a free and open-source source code editor. Prior to 8.9.7, the Notepad++ Windows 11 x64 and ARM64 installer passes the attacker-influenced installation directory `$INSTDIR` from PowerEditor/installer/nppSetup.nsi into a PowerShell `-Command` string used by RegisterMSIX to invoke Add-AppxPackage, allowing PowerShell subexpression syntax such as `$()` in the installation path to execute commands in the installer's security context when the context menu component is selected. This issue is fixed in version 8.9.7.