Ethereum delays Glamsterdam fork on Hoodi testnet after ChainSecurity gas findings
In brief
- Glamsterdam's Hoodi testnet fork, due Monday, is postponed with no new date set.
- ChainSecurity says the gas changes break assumptions contracts rely on when external calls fail.
- ChainSecurity found 13 real-world examples and is in responsible disclosure with affected projects.
- Node operators should revert software or wait for client releases cancelling the fork, researcher Christine Kim said.
What ChainSecurity found
Gas is the fee paid for computing work on Ethereum. Glamsterdam changes how the network charges for creating and accessing stored data through two proposals, EIP-8037 and EIP-8038, and it introduces a separate pool of gas for creating new state.
That's where the trouble starts.
According to ChainSecurity's analysis, those changes break assumptions that many contracts rely on when an external call fails. Some contracts use gas checks (or rely on a call running out of gas) to defend against insufficient gas griefing, where an attacker supplies too little gas so a valid operation fails and gets recorded as a permanent failure. Under Glamsterdam, the firm found, gas can be refilled or returned to a contract after a failed call, and repricing can change how much gas a call needs. ChainSecurity wrote that even with unchanged contract code, a failure path that previously reverted can now complete.
"We already found 13 real-world examples and are in responsible disclosure with the affected projects."
ChainSecurity didn't name those projects. It urged teams to check their contracts and said the Ethereum Foundation is working out how many are affected. The upgrade in question hasn't activated on Hoodi, and it hasn't reached mainnet either.
What node operators need to do
Ethereum researcher Christine Kim said node operators should revert to an older software release without the upgrade scheduled, or wait for their execution client team to ship a new version that cancels it. Preston Van Loon, a developer on the Prysm consensus client, said a Prysm release removing the upgrade from Hoodi's schedule would follow the same day.
Where Glamsterdam stands
Hoodi wasn't the first testnet in line. Glamsterdam went live on Sepolia on October 6 and began producing blocks with a gas limit of nearly 200 million, more than three times mainnet's 60 million. The upgrade also adds block-level access lists, which let computers check transactions in parallel, and it moves the block-builder auction into Ethereum's own rules.
Developers had aimed to ship Glamsterdam on mainnet by the end of 2026, ahead of Hegotá (the next upgrade, expected in 2027). For now, there's no new date for the Hoodi fork.
Frequently asked questions
Why was Glamsterdam delayed on the Hoodi testnet?
ChainSecurity said Glamsterdam's gas changes break assumptions many contracts rely on when an external call fails. Under the upgrade, gas can be refilled or returned after a failed call, and repricing can change how much gas a call needs. The firm said it found 13 real-world examples.
What should Hoodi node operators do after the delay?
Ethereum researcher Christine Kim said node operators should revert to an older software release without the upgrade scheduled, or wait for their execution client team to release a new version that cancels it. Prysm developer Preston Van Loon said a Prysm release removing the upgrade from Hoodi's schedule would follow the same day.
What does Glamsterdam change about gas on Ethereum?
Glamsterdam changes how Ethereum charges for creating and accessing stored data through two proposals, EIP-8037 and EIP-8038. It also introduces a separate pool of gas for creating new state. Gas is the fee paid for computing work on Ethereum.
