Ethereum developers have officially decided to postpone the upcoming Glamsterdam hard fork on the Hoodi testnet after independent blockchain security researchers identified critical gas-related security risks. The discovery has raised substantial concerns regarding how existing smart contracts handle failed transactions under the proposed upgrade parameters, forcing core contributors to reevaluate their immediate timeline and implementation strategy.
The Ethereum Foundation (EF) confirmed the delay in an official blog post, stating that the upgrade—which was originally scheduled to go live on the Hoodi testnet on October 26—would be pushed back. According to the Foundation, the extra time is necessary to allow developers to thoroughly investigate how specific improvement proposals interact with decentralized applications and smart contracts already deployed across the Ethereum network.
The security concerns trace back to an advisory published on October 13 by blockchain security firm ChainSecurity. In their technical analysis, researchers warned that two specific proposals integrated into the broader Glamsterdam upgrade package, designated as EIP-8037 and EIP-8038, could inadvertently weaken long-standing safeguards against a known vulnerability classification referred to as insufficient gas griefing.
This unexpected postponement has inevitably cast a shadow of uncertainty over the broader mainnet launch timeline for Glamsterdam. Prior to the security advisory, Ethereum developers had been tentatively eyeing an early December mainnet deployment, with the universal understanding that a final schedule would only be locked in after observing a smooth and successful rollout across the network’s testnets, including Hoodi.
Gas Changes Could Undermine Existing Smart Contract Safeguards
At the heart of the controversy is a fundamental shift in how transactions and gas allocations are managed under the new rules proposed for the network. In its detailed breakdown, ChainSecurity explained that the proposed modifications could result in unused gas being returned to a smart contract immediately following an operational failure. Under the current, pre-upgrade rules, an operation that runs out of gas or hits a fatal error simply halts execution completely. The new behavior, however, could allow a contract to continue running code when it historically would have stopped.
Researchers noted that this unexpected continuation directly interferes with existing, battle-tested security checks. Many decentralized finance protocols and automated smart contracts rely heavily on precise assumptions about how much gas remains available at any given point during transaction execution to validate state changes and protect user funds.
The security implications directly concern insufficient gas griefing attacks, a scenario where a malicious or adversarial caller deliberately supplies just enough gas for a transaction to initiate, but intentionally leaves too little gas for the legitimate smart contract operation to successfully complete its intended state transition. ChainSecurity warned that Glamsterdam’s proposed alterations could strip away essential safeguards against such malicious vectors. Consequently, vulnerable contracts might erroneously record failed operations as permanently completed or state-finalized.
To illustrate the practical danger, an affected smart contract might mistakenly remove a user’s pending claim or prematurely disable the programmatic option to retry the transaction. This leaves the end user entirely stranded and unable to complete an otherwise entirely valid and legitimate operation, potentially trapping funds or disrupting complex protocol interactions.
ChainSecurity was careful to point out that the Glamsterdam upgrade would not render all gas-related security checks completely unreliable across the board. Certain structural safeguards may continue to function as intended, but the overarching burden now falls heavily on smart contract developers to manually audit and review their codebases to ensure they appropriately account for the radically altered gas rules introduced by the upgrade.
The alarming findings quickly reverberated through the broader Ethereum contributor community, sparking intense debate across developer channels. Weighing in on the discussion via a GitHub comment on October 21, pseudonymous security researcher pcaversaccio characterized the identified risks as serious in nature, joining a chorus of voices calling for an immediate and rigorous reassessment of the hard fork’s readiness.
Adding urgency to the situation, ChainSecurity revealed on Friday that its ongoing investigations had successfully uncovered 13 real-world examples of vulnerable implementations in the wild. The firm stated it was actively coordinating responsible disclosure efforts with the affected project teams to help them mitigate the risk before any network-wide deployment takes place. While ChainSecurity opted not to publicly disclose specific details regarding the 13 instances or name the impacted projects, the firm strongly urged all independent developers to audit their active contracts as quickly as possible.
These fresh security revelations arrive on the heels of an earlier public warning issued by the Ethereum Foundation itself. In that previous advisory, the Foundation cautioned that Glamsterdam’s modified gas model could potentially break a wide range of developer tools, including downstream user wallets, blockchain indexers, and gas estimation utilities that depend heavily on fixed assumptions about how the Ethereum virtual machine handles gas distribution and refunds.
Before the Hoodi testnet delay was announced, the Glamsterdam upgrade had already successfully completed its initial activation phase on the Sepolia testnet on October 6. However, the unexpected friction encountered on the path to Hoodi demonstrates the immense complexity and high-stakes nature of coordinating major protocol upgrades on a decentralized, multi-billion-dollar blockchain network, ensuring that developers will proceed with heightened caution before committing to a final mainnet release date.
