Glamsterdam Takes a Gas Break: ChainSecurity Flags 13 Examples as Hoodi Slips

Ethereum developers postponed the Glamsterdam upgrade on the Hoodi testnet, canceling its October 26, 2026 activation after ChainSecurity identified security impacts involving existing smart contracts. The decision was made during All Core Devs Execution (ACDE) call #248, and no replacement Hoodi date has been set.

The postponement removes the Amsterdam execution-layer activation, the Gloas consensus-layer activation and the planned increase in Hoodi’s gas limit to 200 million from the October 26 epoch. A revised schedule will be announced separately. The stated Q4 2026 mainnet window remains open, with December previously considered as a candidate, although no final mainnet date has been confirmed. Mainnet and ETH holders need no action.

In an October 13 analysis, ChainSecurity said EIP-8037 and EIP-8038 could weaken safeguards against insufficient gas griefing. Under the proposed rules, gas can be refilled or returned to a contract after a failed call, meaning that “Even with unchanged contract code, a failure path that previously reverted can now complete,” the security firm wrote. Researchers said some gas checks would remain useful but would require review, while affected contracts could permanently record failed operations, including removing a user’s claim or disabling a retry.

Concerns reached Ethereum contributors on October 21, when pseudonymous security researcher pcaversaccio described the risks as “serious” and called for a reassessment of the hard fork. On Friday, ChainSecurity said it had identified “13 real-world examples” and was coordinating responsible disclosure with affected projects without naming them. The Ethereum Foundation (EF) had also warned that Glamsterdam’s gas model could break wallets, indexers and gas estimators that rely on fixed assumptions.

Hoodi node operators were directed by Ethereum researcher Christine Kim to revert to an older software release without the scheduled upgrade or wait for their execution client team to issue a version that cancels it. Prysm developer Preston Van Loon said a Prysm release removing Glamsterdam from Hoodi’s schedule would follow the same day. Glamsterdam had already activated on Sepolia on October 6, producing blocks with a gas limit of nearly 200 million—more than three times mainnet’s 60 million. The upgrade changes how Ethereum charges for creating and accessing stored data through EIP-8037 and EIP-8038, introduces a separate pool of gas for creating new state, adds block-level access lists and moves the block-building auction into Ethereum’s own rules. Developers had targeted mainnet by the end of 2026, ahead of Hegotá in 2027.