Withdrawal vulnerabilities enabled bitcoin theft from Flexcoin and Poloniex

Hackers found security weaknesses that allowed them to overdraw accounts with Flexcoin and Poloniex, two websites that facilitate bitcoin transactions, and exploited them to steal bitcoins from the two services. The attacks put Flexcoin out of business and cost Poloniex's users 12.3 percent of their bitcoins.

Story added 5. March 2014, content source with full text you can find at link above.