Arbitrum Blocks New Stylus Activations Amid Sophisticated AI-Assisted Attack Risks

Arbitrum has temporarily blocked new Stylus contract activations on its Arbitrum One and Nova chains due to increasing AI-assisted attacks involving hand-crafted WebAssembly programs. The Security Council made this decision in an emergency action on October 2, citing sophisticated threats that could disrupt chain liveness.

The restriction applies only to new Stylus applications requiring fresh activation, while already-active contracts can continue to run until expiration. Developers can still extend the lifetime of active programs through the permissionless keepalive renewal mechanism.

A separate safeguard has also been implemented on Arbitrum One to delay unconfirmed withdrawals to Ethereum in case of conflicting proofs. If a one-step proof accepts both conflicting answers, it will put settlement on hold, but the chain will continue processing normally.