The Arbitrum Security Council implemented an emergency upgrade on October 2, 2026, at 11:30 EST. This action suspended all new activations of Stylus smart contracts on both the Arbitrum One and Nova networks. Existing Stylus contracts remain operational and can be renewed.
The measure addresses potential vulnerabilities in the Stylus framework, specifically related to unpatched WebAssembly programs. These programs could potentially serve as denial-of-service vectors, impacting network liveness. The pause serves as a preemptive block until future ArbOS updates are released.
Additionally, the upgrade introduced a permissionless guard to the BoLD dispute resolution system on Arbitrum One. This mechanism is designed to mitigate soundness issues by allowing for the suspension of settlements if contradictory proofs are accepted, which may delay unconfirmed withdrawals.
The Arbitrum Foundation plans to collaborate with the ArbitrumDAO to establish a timeline for resuming new Stylus activations. The Foundation emphasized that the identified issues affect network liveness rather than the safety of user funds, which remain secure.
