zkLink

zkLink cross-chain protocol loses about $783,000 in exploit

zkLink◼, a multi-chain zk-rollup protocol, lost approximately $783,000 in an attack on 29 October 2026, according to SlowMist◼. The root cause lies in the Arbitrator contract's claimMessage function, which executes relayer-supplied calldata as the contract itself and reuses a stale transient storage value to pass its consistency check. An unprotected SyncL2TxHashRelayer contract served as the entry point, and the analysis indicates the attacker used this to forge withdrawal batch roots.