haydenaurion: OP, please edit your post to remove that link and to warn others about not clicking it so that we don't get anymore that accidentally click it:
http://www.gog.com/forum/general/i_think_my_account_got_hacked/post33 Thank you.
BKGaming: It doesn't look to do anything harmful though really based on the code, other than through up a popup error with the number 1... still doesn't mean you shouldn't be careful though. Has anyone reported this yet?
EDIT:
But this is pretty interesting and could signify something more is going on...
JDelekto: I can confirm that there is some Javascript injection going on there from the forum itself. You can actually use the Web debugging tool "Fiddler" to see the request/response and then use your developer tools (in my case, F12 in Chrome) to trace through it.
Very clever. :)
BTW, there is a request for userData.json, which is somewhat revealing.
BKGaming: The code injection on the Cities: Skylines wishlist entry does, indeed, currently not do anything remotely malicious (just annoying), it displays a dialogue box with the digit "1" for every link in the page (so, a bunch of boxes). Still though, it does prove that one could, theoretically, use the method to inject truly malicious code.
The data in userData.json is used by the site front-end to -- among other things -- populate the notifications area (get the numbers of friend requests, new chat messages, forum replies, and updates), get the active currency and language, and know which currencies are valid for the current country.