Cascade, a perpetual contract platform backed by institutions including Polychain, was attacked on Arbitrum through its pre-launch locked CLS vault (First Wave invite-only deposits). The attacker accumulated long positions in a low-liquidity market to hedge against CLS short positions, artificially manipulated the mark price upward, triggering large-scale liquidations of CLS short positions. After profiting from the attack, the attacker immediately withdrew approximately $1.34 million USDC. The project team paused trading and withdrawals, and the funds were largely recovered afterward, with full compensation arranged for affected users.