Could Ethereum’s Glamsterdam upgrade slip beyond December?

Ethereum developers delayed the Glamsterdam hard fork deployment on the Hoodi testnet after security experts identified potential gas-accounting adjustments, which could affect the functioning of currently deployed smart contracts during failed transactions.

Thus, the latest update delays Ethereum’s upcoming mainnet hard fork activation indefinitely and casts doubts about its tentative December rollout window.

Glamsterdam timeline in doubt

According to the Ethereum Foundation, the development team delayed the activation due to security concerns in a blog post on Thursday. As the Foundation stated, developers made a joint decision to postpone the update during the ACDE #248 call to evaluate the interaction between the EIP-8037 proposal and currently deployed smart contracts on the mainnet.

Initially, the Hoodi hard fork was set to be activated on October 26 at 17:42:48 UTC at epoch 132,352. Now, this epoch has been removed from the deployment configuration without any new epoch being scheduled.

Additionally, the delay affects the deployment of the Gloas consensus-layer activation and a planned increase in the current Hoodi gas limit to 200 million as part of the Glamsterdam hard fork update package. However, the Foundation emphasized that the schedule change would not affect Hoodi’s existing chain history.

How the gas changes could backfire

This issue goes back to October 13, when blockchain auditing company ChainSecurity marked two proposals from Glamsterdam, namely EIP-8037 and EIP-8038, as a threat to current measures to prevent what it calls “insufficient gas griefing.” As per the attack, the caller sends insufficient gas deliberately so that a legitimate contract function fails.

It will be possible, with the introduction of these measures, to return gas to a contract once an operation fails, thus allowing further operation which otherwise would have stopped.

Many contracts use an amount of gas remaining in the middle of a transaction as one of the security measures. Altering that assumption, it will be possible for the contract to finalize the failed operation, making it impossible for a user to claim anything or perform another operation.

Reminder: you can now sync an ethereum node within half a day and with aggressive settings the space it takes up on disk can be under half a terabyte.

EIP-4444 and hard work by client teams on optimizing snap sync has improved things *a lot*.

Glamsterdam will improve the sync situation further still (eg. Nimbus’s new sync protocol uses it)

— vitalik.eth (@VitalikButerin) September 26, 2026

Some gas checks will withstand despite all changes, but it will be necessary to audit them for Glamsterdam’s new accounting system.

13 real-world contracts flagged

ChainSecurity stated on Friday that it discovered 13 cases of potentially exposed contracts in the real world and was engaging in responsible disclosure with the concerned projects. While ChainSecurity did not reveal the affected projects or details of the discovered cases, it advised developers to assess their contracts urgently.

The news made a strong impact on community members. Pseudonymous developer pcaversaccio commented on October 21 on GitHub that the situation was “serious” and that the fork must be re-evaluated.

Additionally, the announcement comes in the wake of a previous warning by the Ethereum Foundation that Glamsterdam’s new gas pricing mechanism might affect wallets, indexers, and gas estimators operating under fixed assumptions.

Glamsterdam launched on the Sepolia testnet on October 6, while Hoodi was the next checkpoint expected before the mainnet launch.

Initially, the team planned a mainnet launch in December depending on successful testing of the Hoodi testnet. However, since Hoodi is no longer a possibility, the proposed December release should not be viewed as a deadline.