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Ethereum pulls Glamsterdam from Hoodi testnet over gas security risks
Developers cancelled the Oct. 26 Hoodi activation after ChainSecurity flagged gas-related risks to deployed contracts, leaving the mainnet schedule open.
Key takeaways
- Fork pulled. Glamsterdam will not activate on Hoodi at epoch 132,352, and the planned rise in the testnet's gas limit to 200 million was dropped with it.
- Contract risk. ChainSecurity says EIP-8037 and EIP-8038 can let a failure path that once reverted complete instead, undermining defenses against insufficient gas griefing.
- Timeline open. Candidate mainnet dates in early December were contingent on a smooth Hoodi run, so the delay removes the trigger for choosing one.
What happened
Ethereum developers have cancelled Glamsterdam's activation on the Hoodi testnet days before it was due to take effect, after a security review raised concerns about how the upgrade reprices gas. The Ethereum Foundation said in an Oct. 22 notice that the fork would not go live at 17:42:48 UTC on Oct. 26, the epoch 132,352 activation point announced a week earlier. A planned increase in Hoodi's gas limit to 200 million was removed from the schedule alongside it. No replacement epoch has been published.
The review came from ChainSecurity, which published an analysis of the upgrade's two gas proposals on Oct. 13 and said on Oct. 22 that it had "already found 13 real-world examples" of affected contracts while coordinating responsible disclosure with the projects involved. The firm did not name them. EIP-8037 and EIP-8038 change what Ethereum charges for creating state and for accessing or modifying existing state, and add a separate gas pool for state creation.
ChainSecurity's concern is that gas can be returned or refilled after a failed external call, and that repricing can change how much gas an operation needs. Contracts that use gas checks, or that depend on a call running out of gas, to block so-called insufficient gas griefing, where a caller deliberately supplies too little gas so a valid operation fails permanently, may no longer behave as their authors intended. The firm wrote that even with unchanged contract code, a failure path that previously reverted can now complete.
Christine Kim, founder of the research firm Protocol Watch, advised node operators to either revert to an older release without the Hoodi upgrade scheduled or wait for their execution client team to publish a version that drops it. Preston Van Loon of the Prysm consensus client said a release removing the activation would follow the same day. Besu developers merged a pull request titled "Unschedule Amsterdam on Hoodi" on Oct. 22, though the change notes that nodes on Besu 26.10.0 still activate the fork until they run a build containing it. The Ethereum Foundation's Barnabas Busa removed the Amsterdam start time, the Gloas fork at epoch 132,352 and the gas-limit jump from Hoodi's shared configuration files, returning them to their pre-fork state.
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Why it matters
Hoodi was the last public rehearsal before developers picked a mainnet date. The agenda for the Oct. 22 All Core Developers Execution call listed Dec. 1, Dec. 8 and Dec. 9 as candidates, with a decision planned for the following week's consensus-layer call provided Hoodi went smoothly. That sequence is now broken, and the December options should not be read as confirmed targets.
There is also an operational risk specific to the testnet. Validators and builders whose software still expects the old execution rules or consensus duties at the cancelled epoch could fail to follow the canonical chain, so the Foundation is telling operators to check revised client versions and clear stale custom settings rather than assume inaction is safe. More broadly, the episode illustrates how hard it is to change the price of work inside a transaction without disturbing applications that embedded the old numbers in their code.
What the data shows
The cancelled activation was set for epoch 132,352, slot 4,235,264, at 17:42:48 UTC on Oct. 26, pairing execution-layer Amsterdam changes with consensus-layer Gloas changes and a gas limit of 200 million. Glamsterdam went live on Sepolia on Oct. 6, where blocks were produced with a gas limit of nearly 200 million, more than triple mainnet's 60 million. ChainSecurity's count of affected contracts stands at 13. The Ethereum Foundation announced the Hoodi schedule on Oct. 16 and superseded it six days later.
Background
Glamsterdam combines several changes: it moves proposer-builder separation into the protocol under EIP-7732, adds block-level access lists under EIP-7928 so transactions can be checked in parallel, and reprices state-related gas. The Ethereum Foundation had earlier warned that the new gas model could break wallets, indexers and gas estimators built on fixed assumptions, and a transaction replay found most contracts unaffected while flagging a small set that rely on fixed gas stipends, hardcoded limits or remaining-gas logic. The schedule has slipped before: in February the Foundation targeted the first half of 2026, and by September developers were working toward December, with Hegotá expected in 2027.
What is still unclear
It is not yet known how many deployed contracts are actually exposed; the Ethereum Foundation is still working that out, and ChainSecurity has not disclosed the 13 examples. Whether the two proposals need amendment, or whether disclosure and contract-level fixes will suffice, has not been settled. No new Hoodi epoch has been set, and the Foundation has not named a production fork date.
What to watch
The next signals are a replacement Hoodi timestamp, updated execution and consensus client releases that formally drop the Oct. 26 activation, and the Foundation's assessment of how many applications are affected. Whether the early-December mainnet candidates survive will depend on how quickly Hoodi can be rescheduled and completed.
Questions readers ask
Was the Glamsterdam upgrade cancelled?
No. Only the Hoodi testnet activation was called off. Glamsterdam remains on the roadmap and has already run on Sepolia.
What are EIP-8037 and EIP-8038?
Two Glamsterdam proposals that change Ethereum's gas accounting for state. EIP-8037 introduces a separate gas pool for creating new state, while EIP-8038 changes the cost of accessing and modifying existing state.
What should Hoodi node operators do?
They should either roll back to a client release without the Hoodi upgrade scheduled or install an updated release that removes it, and check that custom configurations do not still carry the old activation time.
Sources · 9 publishers
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Ethereum Scraps Glamsterdam’s Hoodi Fork After ChainSecurity Flags Gas Risks -
Ethereum delays Glamsterdam Hoodi testnet launch over security risks
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Ethereum Delays Glamsterdam Hoodi Upgrade Over EIP-8037 Risks -
Ethereum Delays Glamsterdam Hoodi Fork as Developers Test EIP-8037 -
Ethereum Glamsterdam Hoodi Launch Postponed After EIP-8037 Gas Concerns -
Ethereum Glamsterdam Upgrade Delayed Over Smart Contract Security Risks -
Ethereum Delays Glamsterdam Testnet Fork Over Gas Security Flaws -
Glamsterdam is off Hoodi’s October calendar as Ethereum checks contract risks -
Ethereum Delays Glamsterdam Test On Hoodi Over Smart Contract Compatibility Questions
