If you are using GOG Galaxy Client 2.0.17, it is better to check your system if any vulnerability exists.
There is a local privilege escalation vulnerability in GOG Galaxy Client 2.0.17. It occurs when a user installs a game or performs a verify/repair operation. There is a weak file permissions issue and can be exploited by attackers.
Update your GOG Galaxy Client to higher version than 2.0.17 if possible.