In the span of a single week, two prominent Ethereum layer-2 networks—Taiko and Base—faced serious disruptions that rattled confidence in scaling infrastructure. On June 21, Taiko suffered a bridge exploit that compromised its chain-state verification mechanism, while on June 25 and 26, Base experienced two block production outages caused by a sequencer bug. Both projects have since released detailed postmortems, outlining fixes and recovery roadmaps.
Taiko’s Bridge Attack and Staged Recovery
Taiko confirmed that the attack path from the June 21 breach is now closed after independent security experts reviewed the fixes. The exploit stemmed from flawed source-signal proof checks, as noted by security firm Blockaid. Crafted message proofs were accepted on Ethereum without matching valid events on Taiko, allowing unauthorized releases from the ERC20 Vault. In response, Taiko quickly urged users to withdraw bridge funds and asked exchanges to pause TAIKO deposits.
The project now plans a four-step restart: first, deploy fixes and verify the chain’s finalized state with no forged checkpoints; second, replenish the bridge to ensure 1:1 backing of all L2 assets, verifiable on-chain; third, restore network activity including transfers, swaps, and trading; and finally, reopen the bridge under conservative withdrawal quotas. The Security Council will oversee critical actions like unpausing the bridge. Taiko stressed that no user will lose funds and warned against phishing scams posing as recovery sites.
Base’s Sequencer Bug Causes Twin Outages
Base, the Coinbase-backed layer-2, revealed that both its June 25 (116-minute) and June 26 (20-minute) outages shared the same root cause. An invalid transaction failed as expected, but stale journal state remained inside the block builder. When a subsequent valid transaction was processed, it used the wrong state and charged gas incorrectly, producing a block with an invalid state transition that other nodes rejected. This halted block production entirely.
During the outages, transactions accumulated in the mempool until it overflowed, causing eth_sendRawTransaction requests to return errors. While all funds remained safe, the halts disrupted user activity and affected sequencer and validator progress. Base engineers applied a patch to ensure proper journal state updates after failed transactions and identified a second race condition in the engine reset feature that prolonged recovery. The team now plans to strengthen fuzz testing, load testing, monitoring, and add graceful recovery mechanisms to the base-consensus client.
Wider Implications for Ethereum Scaling
The back-to-back incidents highlight persistent vulnerabilities in L2 bridge security and sequencer reliability. Bridge exploits alone caused $28.6 million in losses during May, according to one report, underscoring why proof validation controls and recovery plans are under intense scrutiny. As both Taiko and Base work to restore full operations, the events serve as a stark reminder that even well-established scaling solutions remain susceptible to technical failures and malicious attacks.
