Ethereum developers have officially decided to postpone the highly anticipated Glamsterdam hard fork on the Hoodi testnet following the identification of critical gas-related security risks. These vulnerabilities could fundamentally alter how existing smart contracts handle failed transactions, introducing unprecedented security concerns across the decentralized finance ecosystem.
The Ethereum Foundation (EF) announced that the upgrade, which was originally scheduled to go live on October 26, has been pushed back indefinitely. This delay will provide core developers and independent security researchers with the necessary time to thoroughly investigate how specific improvement proposals interact with smart contracts already deployed on the Ethereum mainnet.
The security concerns first came to light on October 13, when prominent blockchain security firm ChainSecurity published a public warning detailing their findings. According to their analysis, two specific proposals included in the Glamsterdam upgrade package—designated as EIP-8037 and EIP-8038—could inadvertently weaken critical safeguards against a sophisticated type of exploit known as insufficient gas griefing.
The postponement of the Hoodi testnet deployment has naturally cast a shadow of uncertainty over the broader timeline for the Glamsterdam mainnet launch. Prior to these discoveries, Ethereum developers had been actively considering an early December target date for the mainnet rollout, with firm scheduling plans contingent upon a smooth and successful testing phase on the Hoodi network.
Gas Changes Could Undermine Existing Smart Contract Safeguards
In its comprehensive technical analysis, ChainSecurity explained that under the newly proposed rules introduced by the upgrade, gas could potentially be refunded to a smart contract after an operation fails. Under current network conditions, a failed operation would typically cause the transaction execution to halt immediately. However, the proposed changes could allow the contract to continue running past the point of failure, directly interfering with existing security checks that rely on precise calculations of how much gas remains available during the lifecycle of a transaction.
Insufficient gas griefing attacks occur when a malicious caller deliberately provides an inadequate amount of gas for a legitimate smart contract operation to succeed. ChainSecurity warned that the modifications proposed in the Glamsterdam upgrade could thoroughly undermine existing architectural safeguards against such attacks. This vulnerability could theoretically allow contracts to permanently record failed operations as completed or valid states.
To illustrate the severity of this issue, an affected smart contract might inadvertently remove a user’s legitimate claim or permanently disable the user’s option to retry the failed transaction. Consequently, this would leave the user entirely unable to complete an otherwise valid operation, freezing their assets or locking them out of protocol interactions.
Despite the severity of the findings, ChainSecurity clarified that the Glamsterdam upgrade would not render all gas-related security checks completely unreliable. Certain foundational safeguards would continue to function as intended; however, smart contract developers would still need to conduct exhaustive code reviews to ensure their existing safety mechanisms properly account for the upgrade’s new gas-handling rules.
These alarming discoveries quickly prompted widespread concern among key Ethereum contributors and community security experts. Weighing in on the matter via a GitHub discussion thread on October 21, pseudonymous security researcher pcaversaccio described the identified risks as serious, explicitly calling for a comprehensive reassessment of the hard fork’s readiness and design parameters.
Adding urgency to the situation, ChainSecurity revealed on Friday that its automated analysis and manual reviews had successfully identified thirteen real-world examples of vulnerable contracts. The security firm stated that it was actively coordinating responsible disclosure efforts with the affected project teams to help them mitigate the risk before any mainnet deployment.
While ChainSecurity chose not to disclose specific details regarding the thirteen real-world examples or publicly identify the affected projects due to security protocols, the firm issued a stern reminder that decentralized application developers should audit their smart contracts as soon as possible.
These latest developments follow an earlier advisory issued by the Ethereum Foundation, which warned that the broader structural changes in Glamsterdam’s gas model could potentially break various developer tools, third-party wallets, data indexers, and gas estimators that rely on traditional fixed assumptions about transaction execution. Prior to the Hoodi testnet delay, the Glamsterdam upgrade had already been successfully activated on the Sepolia testnet on October 6, marking an initial milestone in its testing lifecycle that is now being heavily re-evaluated.
