@GossiTheDog @jernej__s
Yeah, so this is interesting. I was skeptical, but I can confirm that KB5057589 (which installs KB5055674) for Windows 10 will fail to install if there is a C:\inetpub directory present ahead of time, which a non-admin user can fulfill.
I wouldn't expect the update to be so fragile that the mere presence of a C:\inetpub directory prevents its installation. While KB5057589 is indeed listed as a "Security Update", I can find no information of what CVE(s) it fixes. 🤔