Poloniex Exchange Hack

Digital currency exchange Poloniex has lost 12.3% of its total bitcoin supply in an attack.

The exchange took to Bitcoin Forum on 4th March to report it had been compromised by a previously unknown vulnerability in its coding:

https://bitcointalk.org/index.php?topic=499580

Poloniex owner Tristan D'Agosta:

"The hacker discovered that if you place several withdrawals all in practically the same instant, they will get processed at more or less the same time. This will result in a negative balance, but valid insertions into the database, which then get picked up by the withdrawal daemon."

D'Agosta also stated that Poloniex compensated users:

"97 BTC were taken and 97 BTC were paid back. Although the value of bitcoin fluctuated, it is not very different now from what it was in the beginning of March."