Arbitrum's Security Council temporarily blocked new Stylus contract activations on Arbitrum One and Nova in an October 2 emergency action. Arbitrum attributed the precaution to increasingly sophisticated AI-assisted attacks involving hand-crafted WebAssembly programs outside the standard Stylus compiler toolchain. Already-active Stylus applications can continue running, while ordinary Solidity deployment and execution remain unaffected, according to the Council's action report. Arbitrum said known Stylus bugs primarily threaten chain liveness and that no attack permitting theft of user funds had been discovered. A separate safeguard would suspend Arbitrum One's settlement to Ethereum if a one-step proof accepts conflicting answers, delaying unconfirmed withdrawals while One continues processing. The official notices give no date for restoring activations.