That block was mined late June, did this exploit have something to do with wallet problems during summer? I mean there were speculations about bad nodes and stuff like that?
About chinese exchanges, they are all going to close down. Not sure how many of those are going to have a new life somewhere else than in mainland china but it's safe to say that btc38 and bter are going to be closed soon.
I cannot really remember what was happening at that time but I don't think there was any active development on Cryptonite in that period and the block explorer was down, which is probably why it went unnoticed. I doubt the exploit had anything to do with wallet problems, the wallet has always been fairly buggy until recently, but many of those stability issues have been solved over the last few months.