New Arbitrum Stylus contracts, frozen on Arbitrum One since 2 October, could be switched on again under a proposal posted to the Arbitrum DAO governance forum on Friday 23 October at 18:48 UTC. The Constitutional AIP “Stylus Activation Contract” would let developers activate a new Stylus program only after a limited audit by an Arbitrum Security Program auditor and a signature from a multisig controlled by the Arbitrum Foundation. The DAO would keep the power to revoke that role at any time. No vote has been scheduled.
For now it is only a forum post. At about 05:00 UTC on Saturday 24 October the thread, published from the forum account named offchain, had one message, no replies and 27 views. The Arbitrum Foundation’s Snapshot space showed no temperature check on Stylus, the first formal step of the vote. Until the whole process has run, new activations stay blocked.
The question the text tries to answer is narrow: how to let teams ship Stylus code again without reopening the door that worried the Security Council. Until 2 October, activating a contract only took a transaction and the blockchain come Ethereum. Il gas misura il lavoro di calcolo richiesto da una transazione e la commissione è pari al gas usato moltiplicato per il prezzo unitario del gas.">gas to pay for it. Under the plan, it would also take an auditor’s pass and a Foundation signature.
Why the Arbitrum Security Council froze Stylus activations on 2 October
The pause came in a Security Council emergency action completed “at 11:30 EST on 2nd October 2026”, according to the Arbitrum forum report. US Eastern time was on daylight saving that day, so this matches 15:30 UTC; the report went up at 15:31 UTC. The Council gave the reason in one sentence: “AI-assisted tooling has led to an increasing number of sophisticated attacks on hand-crafted WASM programs that do not use the standard Stylus compiler toolchain.”
Hand-crafted means written directly as WebAssembly bytecode instead of being compiled from Rust or C by the official tools. The Council said such programs are built to cause unexpected behaviour, for example degrading the chain’s performance for every other user. It also wrote that “no attacks have been discovered that permits theft of user funds”, and that known Stylus bugs mainly affect chain liveness, through denial of service.
New ArbOS releases had already patched several reported bugs and known attacks over the previous months, the report said. The pause was taken “out of an abundance of caution”, the post says, to stop new hand-crafted programs exploiting flaws the current ArbOS has not fixed yet. The post does not list the bugs, the versions that fixed them, who found them or whether any attack happened on the live network. CryptoSlate, which reported the pause on 3 October, relayed Arbitrum’s explanation without checking the link to AI tools on its own.
Technically, the freeze is a single setting. The Council called ArbOwner.setWasmActivationGas with the largest possible value (2^64 minus 1) on Arbitrum One and Arbitrum Nova, which makes activation so expensive in gas that it cannot succeed. Because only one configuration parameter changed, no ArbOS upgrade and no audit were needed, the report said.
The same payload carried a second, separate measure: a permissionless guard on BoLD, the dispute system that secures Arbitrum One’s settlement on Ethereum. Anyone who shows the guard two conflicting answers to the same step of an open challenge, both accepted by the one-step proof, can make the guard put Arbitrum One’s settlement to Ethereum on hold. Arbitrum said it added the guard “given the rise of AI-assisted attacks”. The chain would keep running, but messages to Ethereum that are not yet confirmed, such as withdrawals, would wait while the Council deploys a fix. That guard had an external audit, whose author the post does not name.
Arbitrum is not alone in reacting to bugs found faster with AI help. On 23 October, the day the Stylus proposal appeared, Bitcoin Core changed its own disclosure rules for bugs that AI tools can find, as covered in our report on Bitcoin Core dropping its embargo for bugs an AI can find.
What Arbitrum Stylus is and why activation matters
Stylus adds a WebAssembly virtual machine next to the EVM on Arbitrum, so smart contracts can be written in Rust, C and C++ and call Solidity contracts, and the other way round. The Arbitrum blog announced it on 31 August 2023, saying computation was “over 10x improved” and memory “over 100x improved” compared with Solidity. Those are Arbitrum’s own figures. Stylus reached Arbitrum One and Nova on 3 September 2024 with the ArbOS 31 “Bianca” upgrade, The Defiant reported at the time.
A Stylus contract goes live in two steps. Deployment puts the WebAssembly code on chain, and anyone can still do that today. Activation then compiles the deployed code so the chain can execute it. The proposal’s own definitions are blunt: a deployed Stylus contract “cannot be called until it is activated”. Blocking activation is therefore enough to stop new Stylus code from running, without touching deployment or existing contracts.
Activation also has an expiry. By default it lasts 365 days, and anyone can renew it through a keepalive call, according to the Arbitrum docs notice on the pause. Arbitrum One is a rollup that settles on Ethereum, and Stylus lets it run WebAssembly programs, which EVM-only layer 2 networks do not support.
How the Foundation sign-off would reopen Stylus on Arbitrum One
The proposal keeps the Council’s gas setting in place and adds a way around it for approved code. Section 4 of the text describes the route a developer would follow:
- The developer sends the source code and build configuration, with any information the Foundation reasonably asks for, and accepts the Foundation’s activation terms.
- An auditor from the Arbitrum Security Program performs a limited audit. At a minimum, it rebuilds the program with cargo stylus from the submitted commit and checks that the bytecode matches the deployed codehash.
- The auditor posts a pass or fail result on the Arbitrum governance forum.
- On a pass, the Foundation gives the developer an activation signature.
- The developer activates the contract by sending the transaction through the new Stylus Activation Contract.
The rebuild check is the heart of it. A program that comes out of the standard toolchain from published source cannot be hand-crafted WebAssembly, which is the category the Council blamed for the attacks. The audit is meant to judge whether a contract could harm the Arbitrum protocol. It does not review the contract’s business logic, and the proposal says plainly that it is no assurance that a contract’s business logic is free of bugs.
On chain, the Stylus Activation Contract would run four actions in a single transaction: check that the caller is authorised for that contract, lower the activation gas requirement for a moment, activate the approved code, then restore the restrictive setting before the transaction ends. A failed call reverts, so activation is never left open. The design is also meant to stop one approval from being used to activate extra, unapproved code. Any new version needs a new audit and a new signature.
The scope is Arbitrum One only, using capabilities already in ArbOS 61, so no ArbOS upgrade is needed. Arbitrum Sepolia, the test network, is outside the proposal but will follow the same process, the text says. Arbitrum Nova is left out “because it is minimized”, and nothing in the proposal reopens activations there. Independently governed Arbitrum chains are handled separately.
Who holds power under the Stylus activation contract
Four parties appear in the text, plus the Security Council whose setting stays in place. Their roles, as the proposal describes them:
| Party | Role under the proposal | Limits stated in the text |
|---|---|---|
| Arbitrum DAO | Sole administrator of the activation contract; grants, revokes or reassigns the signing right and changes the configuration | Acts through constitutional votes, with their governance waiting periods |
| Arbitrum Foundation | Holds the signing right through a multisig and manages its own signers | Does not perform the audit or make its own security assessment; cannot deactivate a contract |
| Security Program auditor | Performs the limited audit and posts pass or fail on the forum | Checks harm to the protocol, not business logic; firms not named |
| Developer | Submits code, accepts the Foundation’s terms, sends the activation transaction | Needs a new audit and signature for every new version |
| Security Council | Its 2 October gas setting stays in force and is bypassed only for signed code | A vote against the proposal does not lift the pause |
The Foundation’s mandate would be “ongoing” from implementation, with “no automatic expiry”. It ends only if the DAO changes or revokes it. The multisig address and the signer setup are not public yet; the proposal promises them before the on-chain vote, together with the source code, deployment addresses and governance payload.
The Foundation would also lean on others for the decision itself. In the text, it “does not perform the audit and does not make its own assessment” of a contract’s security, and relies on the result the auditor posts. The signature, an offchain one in the proposal’s definitions, confirms that the code is eligible for activation based on that audit.
What stays permissionless for Stylus contracts, and what does not
A large part of Stylus keeps working as before. The proposal and the Council report agree on what is untouched:
- Solidity and EVM contracts are not affected, in deployment or execution.
- Anyone can call any activated Stylus contract, old or approved through the new route.
- Active contracts keep running until they expire, 365 days after their last activation or renewal on Arbitrum One. The ArbOS 61 upgrade renewed all of them, so none expires before 20 August 2027, the Council said.
- Anyone can still renew an active contract through keepalive.
What would go through the audit and signature: any new Stylus code, including a new version of an existing application, and the reactivation of a contract that expired or needs updating after a Stylus version change. A team running a Stylus app today keeps its live contract, but any upgrade it wants to ship waits for the new route.
The proposal also points further ahead. “Protocol-level activation controls” and a way to deactivate Stylus contracts are planned for a later ArbOS proposal, which this AIP does not authorise.
The risks the proposal lists for its own design
The text has a section called “Risks and Tradeoffs”. No delegate or builder had replied in the thread when we checked, and Coindaro found no published criticism of the plan, so the points below are the proposal’s own.
Builders would depend on the availability of the auditors and of the Foundation for every new activation. The proposal names audit or signing delays, refusals and loss of access to the signer as causes of delayed launches and updates. Requests would be handled on a “reasonable efforts” basis, not on a fixed schedule, with turnaround tied to submission volume, auditor capacity and code complexity.
Because the mandate has no expiry, moving the signing right to someone else would take a governance action. A limited audit, the text adds, “cannot guarantee that every activated contract is safe”, and “a compromised signer could provide an activation signature for harmful code”. There is still no mechanism to deactivate a contract once it runs.
The activation contract itself needs chain-owner permissions. Its access controls, upgradeability and handling of the temporary gas change are to be audited by Trail of Bits, whose report should be published before the on-chain vote.
Coindaro’s reading (this is our analysis, not a reported reaction or a quote from the proposal): the plan swaps a blanket freeze for a per-contract gate where an auditor decides and a single organisation signs, on a step that until 2 October anyone could take. The text keeps real checks, from DAO control over the signing right to the Foundation’s lack of power to switch contracts off. The Foundation has also faced DAO pushback before. In April 2023 token holders voted heavily against AIP-1, after 750 million ARB, worth about $1 billion at the time, had already been moved to the Foundation, The Block reported. We cite that episode as background only; it says nothing about how delegates will vote on Stylus.
No vote date yet: the steps before Stylus reopens
The proposal sets out an order of steps but no dates:
- Discussion on the forum, the current stage.
- A temperature check on Snapshot.
- Implementation and review: the activation contract and payload are finalised and tested, and the Trail of Bits report, source code and addresses are published.
- An on-chain vote on the Constitutional AIP, with FOR, AGAINST and ABSTAIN options.
- If approved, the required governance waiting periods, then execution on each affected chain.
Activations through the new route can only start once that execution is done and the process is running. The proposal adds one point that matters for anyone hoping a “no” vote would simply restore the old rules: a vote AGAINST “does not automatically lift” the Council’s pause, and a different activation policy would need its own governance action.
Several facts are still missing. The text gives no date for the Snapshot or the on-chain vote, and no date for reopening. It does not name the auditors, say what a limited audit would cost or who pays for it. The DAO would not fund anything new: the Foundation and its service providers carry the engineering of the activation contract and the coordination of its audit, which is a different thing from developers’ own audits. The multisig address and signers are unknown, and so is the number of Stylus contracts or teams waiting to activate.
What Stylus builders can watch for
Developers would be able to send requests to [email protected], the proposal says, and the Foundation would post the Terms of Use for the activation contract if the DAO approves it. Teams with live contracts have until at least 20 August 2027 before any expiry, and keepalive renewals still work.
The DAO’s Stylus Sprint grant programme has already ended. A Stylus Sprint Retrospective posted to the forum on 23 October at 19:08 UTC, prepared by Entropy for the Stylus Sprint Committee, says the report was completed before the 2 October action and that its recommendations reflect conditions before the pause. Grants left partly completed are going through the Foundation’s termination process, and Entropy expects the remaining funds back with the DAO “in a few weeks”.
The next date to watch is the Snapshot temperature check, which had not been posted on 24 October. Arbitrum’s next fixed date on the token side is unrelated to Stylus: the final ARB team and investor unlock in March 2027.