Arbitrum has stopped new Stylus contract activations on its main networks after spotting AI-powered attacks using custom WebAssembly code. Existing Stylus apps keep running, but developers now face an open-ended pause on new launches.
Developers on Arbitrum's Layer 2 networks have hit a sudden stop. The protocol's Security Council has blocked all new Stylus contract activations. This emergency move comes after the team found new AI-driven attack methods. Existing Stylus apps keep working, but no new programs or updates that need activation can go live on Arbitrum One or Nova for now.
AI attack risks and how Arbitrum responded
The Security Council says the pause is because of a spike in advanced attacks using hand-written WebAssembly code. These attacks can get around the normal Stylus compiler. The Council says these exploits target known Stylus bugs that could threaten the chain's liveness, including possible denial-of-service attacks. No user funds have been stolen so far, but the Council says the threat is serious enough to act right away.
The gas requirement for Stylus activations was raised to an effectively unreachable level, technically blocking new deployments without impacting existing contracts.
To enforce the block, Arbitrum raised the gas needed for Stylus activations to a level no one can pay. They did this by changing the setting ArbOwner.setWasmActivationGas(2^64 - 1). This lets existing contracts keep running as normal, but stops any new activations at the protocol level. No ArbOS upgrade was needed for this change.
What this means for developers and users
Regular Solidity contract deployment and execution are not affected. Most decentralized apps and smart contracts on Arbitrum keep working as usual. But developers who use Stylus for extra features or better performance are now stuck. There's no timeline for when new activations might start again. The Arbitrum Foundation says it will work with ArbitrumDAO to decide when and how to reopen Stylus activations, but there's no set date or process yet.
At the same time, the Security Council added a new safeguard for BoLD's one-step proofs on Arbitrum One. If two different answers are submitted for the same step in an open challenge and both are accepted, the network will pause settlement to Ethereum until a fix is in place. While this pause is active, Arbitrum One keeps processing transactions, but messages to Ethereum-including withdrawals-are delayed until the problem is fixed. Withdrawals are not paused by default; delays only happen if this specific conflict comes up.
Stylus enables developers to write smart contracts in languages like Rust and C++ that compile to WebAssembly, offering greater flexibility and performance compared to Solidity. However, this expanded programmability introduces new attack surfaces, requiring robust security measures as the protocol evolves.
Security moves across the blockchain world
Arbitrum's decision to freeze new Stylus activations fits a wider trend. Blockchain networks are moving fast to block real security threats. For example, as reported earlier, Kraken kept EGLD trading locked after MultiversX had a network halt from an attempted exploit. This shows how exchanges and protocols are now more willing to put security first, even if it means stopping service.
For Arbitrum, the main risk right now is not stolen funds but possible chain disruption. The Council's move shows how hard it is to protect programmable blockchains as attack methods change, especially with AI tools making it easier to create new exploits. The open-ended pause on Stylus means the bugs are not easy to fix and may need bigger changes to the protocol or its tools.
As of now, Arbitrum has not given any timeline for bringing back Stylus activations. The Foundation's plan to work with ArbitrumDAO means both governance and technical review will shape what happens next. For now, developers have to wait for more news. Users of current Stylus-powered apps can keep using them as normal.
Stylus lets developers write smart contracts in languages like Rust and C++ that compile to WebAssembly. This can bring better performance and more flexibility than Solidity. But the current freeze shows the trade-off between adding new features and keeping the network secure, especially as new attack risks appear.
