As in title. What’s your experience with it? If something isn’t executable, then it has to exploit vulnerability in order to run anything malicious. But does it happen often with mp4, mkv and other files like mp3 or epub?
I assume that if I use updated linux, then I’m mostly safe?
Typically is not possible. Those media files are basically just data files (e.g. like a .txt text file) so media players normally do not look for anything to execute inside them. And frankly people should avoid any media player attempting to execute random code found in media files.
Case in point, the old Windows Media Player + old .wmv files used to be able to direct people to random websites to download/execute malware. Leave it to Microsoft to somehow turn a movie file into malware https://security.stackexchange.com/questions/106188/can-a-rogue-wmv-file-hijack-windows-media-player