Scroll has fixed a serious vulnerability that could have allowed an attacker to withdraw funds from its bridge. The network said the flaw was not exploited. The emergency upgrade was also the first such fix since Scroll removed its independent Security Council, meaning it went live under an upgrade path that requires no outside sign-off.

Bug in proof-verification contract

The vulnerability was found in the ZkEvmVerifierPostFeynman contract, which verifies the proofs Scroll uses to post new states to Ethereum (ETH). In a post-mortem published on Scroll’s governance forum, the project said the contract manually constructed its call to OpenVM’s Halo2 verifier and used the first four bytes of a user-provided proof as the call label. On Ethereum, those first four bytes are the function selector that routes a call to a specific function, which is what gave a user-supplied proof the ability to steer execution.

OpenVM’s verifier includes a verify function with the selector 0x24270d54. When a proof began with those four bytes, the contract routed the call to verify rather than through the intended path. The function then obtained its parameters from locations an attacker could control.

This could have allowed an attacker to present an old, valid proof as evidence for a new input. The resulting state root and withdrawal root could then have been falsified and recorded on Ethereum — the kind of failure that turns a bridge’s own verification layer into the attack path. Bridge exploits have historically ranked among crypto’s costliest incidents: the Ronin Network bridge lost more than $600 million in a March 2022 attack, and Wormhole lost roughly $320 million weeks earlier.

Earlier versions of the contract were not affected because their verifiers did not have a function selector, meaning every call followed the normal route. Under the patched design, all calls go through a single entry point, with the contract—not the proof—setting the relevant parameters.

Scroll credited ethical hacker ZHOUCHUNGONG with reporting the vulnerability on Nov. 3, one week before the fix was published.

Scroll says finalizations were checked

Scroll said the flaw was not exploitable during the period in question. An attack would have required either the permissioned prover role or “enforced batch mode.” That mode becomes available only after seven days without a finalization, and that condition did not occur.

The project rechecked all 748 finalizations completed while the vulnerable contract was active. It also replayed 233 earlier finalizations on a copy of Ethereum mainnet. According to Scroll, all of the checks produced the same roots.

Security Council replacement

Previously, outside members helped oversee Scroll’s emergency upgrades. In May 2025, the project deployed a fix for its FRI verifier, while a verifier replacement in February 2026 was also approved by the Scroll Security Council. The council had 12 members, with nine required to approve an action.

Scroll removed the council on June 1, 2026, replacing it with a 3-of-4 administrative multisig controlled by the Scroll team. The network subsequently lost its Stage 1 decentralization rating and is now listed at Stage 0, the lowest tier in L2BEAT’s staging framework, which grades how far a rollup’s proofs and exit paths reduce users’ reliance on trusted operators. The multisig can upgrade core contracts, including the bridge, without a delay, meaning a fix like this one now proceeds on the multisig’s signatures alone.

Scroll initially proposed dissolving the council in April, arguing that its cost exceeded its value. Some forum participants opposed the move, questioning why the project would not retain a smaller council and who would approve network actions in the future.

A proposal posted to the Scroll DAO forum on Nov. 4, 2026, would turn the chain into a private, invite-only network centered on artificial intelligence if approved. It also says the SCR token would move back to Ethereum mainnet, where holders would use it for voting and staking. How that proposal fares, and whether Scroll’s Stage 0 standing changes while the team multisig retains delay-free upgrade authority over the bridge, remain open questions.

According to L2BEAT, Scroll’s total value locked had fallen by April from about $600 million in 2024 to approximately $24.3 million. The figure was about $6.6 million as of the report. The SCR token was trading at approximately $0.018, nearly 99% below its 2024 high, according to CoinMarketCap.