Unable to open hyperlinks to audio and video files in O365 applications with Windows Media Player as default after update KB5015807

Amanda Kaczowka 1 Reputation point

After updating to KB5015807 users in our organization are unable to open hyperlinks to audio and video files from O365 applications (for e.g. Excel or Word) when Windows Media Player is the default program for both music and video player. The files types that have been tested are .wav and .asf. We are able to open these files through hyperlinks when we change the default music and video player to VLC. Location of file does not matter with regards to being saved to a network share or local hard drive.

Upon investigation, we discovered a registry string value called LegacyDisable for the "Open" registry key in HKEY_CLASSES_ROOT\WMP11.AssocFile.WAV\shell\open. The default permission to the "Open" registry key are "read" for system and local administrators and only full control to TrustedInstaller . Where as \HKEY_CLASSES_ROOT\VLC.wav\shell\Open for e.g., default permission for the Open registry key for system and local administrators is "full control". This has lead us to believe this may be intended behavior for a possible security vulnerability with the Windows Media Player software. I'm looking to confirm if this was deliberate or if there is a fix for this as our users currently do not want to change their default music and video program to VLC and would like to continue use Windows Media Player.

When I deleted the string value for LegacyDisable I was able to open hyperlinks to .wav files without error in both Excel\Word with Windows Media Player being the default program.

Windows 10
Windows 10
A Microsoft operating system that runs on personal computers and tablets.
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