The vulnerabilities concern the QuickTime player. From what I recall, GOG's games use QuickTime Alternative, which passes the QT codecs to another video player, especially since Myst and so on use an ancient version of QuickTime that wasn't supported even a few years back.

I think it should be fine, but not 100% sure about it.

Edit: Vulnerabilities, not vulnerability. At least two of them so far.

I was wondering about Gog's position in this. Glad to see we're safe. Any idea if Steam will be brought to its knees by this? =P

In a larger picture, it is Microsoft that should be worried. Steam will probably at most post a simple announcement or adopt zero fuck given stance.

Not very familiar with this, do those games install a/the quicktime player system-wide, so that it will gladly play content on random web pages and whatnot? Or do they maybe just use a private instance that only ever gets called to play the games own cinematics?

The former case might be of concern. The latter probably not, unless you suspect that those particular cinematics are out to hack you.

And in the end, why would it influence Steam at all? To my knowledge Quicktime hasn't been a thing in games since the end of 90's FMV flood.

The current version of QuickTime works fine with Myst and Silent Hunter II and the QTA hasn't been developed for 5 years, so I don't know how well it plays on modern Windows.

Honestly I don't mind security vulnerabilities in QuickTime, both because it's a very niche piece of software unlikely to be used as an attack vector and also because the vulnerabilities require user interaction (i.e. open a malicious file) which is a pretty high bar IMO.

Apple may have stopped development of QuickTime, but it works for me for the very limited purpose of running two gog.com games that I own.

Do the GOG games install QuickTime or QuickTime Alternative?

The gog.com installer of Silent Hunter II offers to install "QuickTime Player", but doesn't specify what version or whether or not it's the Alternative. Myst and Riven offer to install QT Lite 4.1.0 (the stripped down version of QuickTime Alternative).

Many years ago I used to download the codec only but nowadays the games work anyway. Maybe the codec included in VLC or some such? This works just fine for disc versions of old games.

Yes, but Steam does have many games from that decade, such as the Myst series.

Which I doubt sell enough there for the death of QT to have any effect at all.