On Arbitrum, Ostium, a decentrified and lasting contract trading platform, was attacked by a prophecies machine, and about $18 million USDC came out of the protocol liquidity vault. The security company Blockaid stated that the attackers had made false profits by falsifying price reports and had completed the withdrawal of funds.

Attack with signature key

According to Blockaid, the assailants controlled the premonitioner signature key and used a registered PriceUp Keep transponder to submit future time price reports with authorized signatures, thus manipulating Ostum ' s price-feeding system.

In the process, the agreement settled the non-existent profit position and subsequently paid a large sum to the attackers. Ostium subsequently stated on platform X that the team had noticed that the OLP vault was abnormal and had suspended all transactions and was investigating the incident.

About a third of liquidity outflows

Ostium is deployed on Arbitrum, which offers long-term contractual transactions linked to real-world assets such as equities, commodities, foreign exchange and indices. At the time of the incident, the total value of the agreement was approximately $63 million, a loss close to one third of its liquidity.

  • Damages of approximately $18 million
  • Outgoing assets are USDC issued by Circle
  • All transactions were suspended after the agreement.

DeFi, security incidents continue to increase.

It was reported that during the first five months of 2026, the DeFi agreement had stolen over $840 million. Of this amount, KelpDAO lost approximately $292 million and Drift Protocol lost approximately $285 million. In June, Resolv Labs was also attacked, at a loss of over $25 million.

Some security researchers believe that AI tools are accelerating the detection of loopholes. Previously, security practitioners indicated that existing models had been able to faster check codes and identify potential deficiencies. In May, researchers also discovered a four-year-old forgery gap in Zcash using the Claude Opus model of Anthropic.