Some of the exploits' effects have been noticed and cleaned up (by moderators?). I am not in touch with any of them as of now but "they" are probably aware of at least one of the issues - I'll wait for the coming working days.

You have to crack SHA1 hash first

"exploits' effects"?

Are my games in danger?!?

Please don't let this shift into a wrong direction. Nothing is in danger. I am trying to responsibly disclose security vulnerabilities to gog.com. There's no real need to further discuss the issues here. All I am asking for is an official contact from gog.com to discuss these issues with. Please don't reply to this thread any longer, thank you :)

So do I. But if there's nothing we (the users) can do, and only GOG staff can fix it, the way to go is not making the vulnerabilities public so any random malicious hacker can exploit them.

good point.

You run a hotel. I, as a guest, find out that by taking the keycard to my room and pressing it on a specific point to the side of the soda vending machine on the lobby I can turn my keycard into a skeleton key that can open any of the hotel rooms. Do I contact you, the hotel owner about it, or do I tell each and every one of the guests, so they can better protect their valuables?
There are cases when it's better to inform the users, and cases where it's better to not (immediately) inform them but allow the exploit to be fixed first.

I run a B&B in the middle of nowhere. We don't even have locks on the doors. XD No one up here does.

Hotel related example, not specific to you. After all, you don't even have a soda vending machine in the lobby (or do you?).
But no worries either way.

We don't have a vending machine but our guests have full use of the house, including everything in it, be it coffee, tea, soda, beer, wine, food, free of charge.

Sometimes I get a little pissed when some asshole comes in and drinks all my Coke, but I'd rather have a happy guests than a thirsty one. :P

If this is about the forum, all I can say is that it's a leaky roof and GOG already has plenty of buckets in place. Will they fix the roof? Probably not. It needs to be replaced anyway.

So anyone can just march into my room nekkid, and start doing helicopter with their dick? What kind of business exactly are you running there?!?

Probably one where guests who complain end up like in Bates Motel.