Arbitrum-based DEX Ostium targeted in $18 million vault exploit: Report

Arbitrum-based DeFi protocol Ostium has halted trading after a reported exploit in its OLP vault led to an estimated $18 million USDC loss. Security firm Blockaid, the first to report the incident, said the attacker manipulated oracle data to generate fake trading profits.

🚨 Blockaid detected an @Ostium Vault exploit on Arbitrum.

An attacker used a registered PriceUpKeep forwarder and future-dated authorized oracle reports to create artificial trade profit, triggering a ~$18M USDC payout from the vault.
More details in 🧵

— Blockaid (@blockaid_) July 15, 2026

Blockaid said the attacker used a registered PriceUpKeep forwarder and future-dated authorized oracle reports to fabricate trading profits, allowing them to extract roughly $18 million USDC from the vault.

Ostium said it was aware of the incident. The project has suspended all trading activity, and is actively investigating the issue.

We are aware of the issue with the OLP vault. We have paused all trading. The team is investigating.

— Ostium (@Ostium) July 15, 2026

Ostium provides perpetual trading for tokenized real-world assets, giving users onchain access to markets beyond crypto. The project recently secured $20 million to grow its decentralized platform for trading real-world assets via perpetual futures.