Ethereum Delays Glamsterdam Hoodi Fork After 13 Real-World Examples

By Tom Whitfield

Ethereum developers postponed Monday’s Glamsterdam hard fork on the Hoodi testnet after ChainSecurity found 13 real-world examples of contracts that could permanently record failed operations their code was designed to keep retryable.

ChainSecurity said on Thursday, October 22, 2026, that it had entered responsible disclosure with the affected projects. No new Hoodi activation date has been set.

The auditor wrote in a blog post: “It has just been decided to delay the Glamsterdam hard fork on the Hoodi testnet because of security impacts we identified.”

Why was Monday’s Hoodi activation postponed?

Glamsterdam had been scheduled to activate Monday, giving node operators a defined software target ahead of the fork. Ethereum researcher Christine Kim said operators should either revert to an older release without the upgrade or wait for their execution-client team to release a 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. The immediate operational task is to remove the scheduled upgrade from client software before any Hoodi activation proceeds.

How does the gas change create risk?

Gas is the fee paid for computing work on Ethereum. Glamsterdam changes how the network charges for creating and accessing stored data through EIP-8037 and EIP-8038, and introduces a separate pool of gas for creating new state.

Many contracts use gas checks, or rely on a call running out of gas, to stop an attacker from deliberately supplying too little gas. The intended protection leaves a valid operation eligible for retry instead of letting insufficient-gas griefing force a permanent failure.

Under Glamsterdam, gas can be refilled or returned to a contract after a failed call. Repricing can also change how much gas a call needs, altering behavior even when developers do not change contract code.

ChainSecurity wrote: “Even with unchanged contract code, a failure path that previously reverted can now complete.” The auditor urged projects to check their contracts and model gas use, replenishment and failure paths on external calls.

The review matters even when a project has not changed its contract code. The Ethereum Foundation is working out how many contracts are exposed. Its count will establish the scale of exposure, while ChainSecurity is contacting affected projects as part of responsible disclosure.

What has Glamsterdam already changed?

Sepolia, another Ethereum test network, activated the upgrade on October 6 and began producing blocks with a gas limit of nearly 200 million. The limit is more than three times mainnet’s 60 million, giving Sepolia a larger per-block testing allowance.

Glamsterdam also adds block-level access lists, which let computers check transactions in parallel. It moves the auction that decides who assembles each block into Ethereum’s own rules.

What is the next deadline?

Developers had aimed to ship Glamsterdam on mainnet by the end of 2026, ahead of Hegotá. Hegotá is expected in 2027 and could add native privacy features.

The immediate checkpoint is a revised Hoodi software release and replacement testnet schedule. No new Hoodi date has been announced, and developers’ prior target placed Glamsterdam on mainnet by year-end 2026.