GMX officially disclosed the reasons and follow-up measures for the approximately $40 million attack on GMX V1 on the Arbitrarum chain on July 9th. According to the analysis of the security team, the attack originated from a re-entry vulnerability in the OrderBook contract. Hackers used this vulnerability to manipulate the average short price of BTC, thereby significantly raising the GLP price and arbitrage. The official has suspended transactions related to the Avalanche chain, confirmed that the V2 version is not affected, and will take measures such as disabling GLP casting and redemption, and setting up compensation pools. GMX reminds V1 fork project to promptly fix similar risks.