Ethereum developers have approved a fix for a deposit-handling flaw in the upcoming Glamsterdam upgrade. The issue could have caused ETH intended for a new validator to be credited to a block builder instead, even when both used the same public key.
The correction was merged into Ethereum’s consensus specifications on October 26, following an initial rejection and additional testing.
The flaw was identified by researcher avsetsin, who reported on October 12 that the planned Gloas upgrade could mishandle deposits waiting to be processed during the network transition. Under the proposed rules, if a builder registered with a public key before a validator deposit arrived using that same key, the deposit could be credited to the builder.
This could create problems for staking services that send funds to establish new validators. If the deposit went to a builder-controlled account instead, the intended validator might never be created, potentially leaving the staking service unable to complete its normal deposit and recovery process.
The researcher examined possible exposure involving Lido, Origin, and Rocket Pool. However, the findings depended on how each protocol handled deposits, and no actual exploit involving these projects was established.
The issue relates to Glamsterdam’s planned proposer-builder separation, which gives block builders responsibility for assembling transaction payloads while validators handle block proposals and confirmations.
Developers initially rejected the proposed fix on October 19 because it lacked sufficient support from client teams. They reopened the proposal on October 23 after further review. Additional tests were then added to cover situations where builder and validator deposits use the same public key but require separate treatment.
The final correction was merged on October 26. It uses withdrawal credentials to distinguish validator deposits from builder deposits, ensuring that each is directed to the appropriate account.
Meanwhile, Ethereum developers have delayed Glamsterdam’s activation on the Hoodi testnet because of a separate smart contract compatibility issue involving EIP-8037.
The Ethereum Foundation postponed the planned October 26 activation while researchers investigated how the change could affect existing contracts. The delay also pushed back the planned execution and consensus upgrades, along with the proposed increase in the gas limit to 200 million.
Ethereum researcher Toni Wahrstätter warned that EIP-8037 could interfere with smart contracts that rely on assumptions about the amount of gas available during execution. In some cases, this could cause transactions to fail unexpectedly or allow execution paths that developers believed were unreachable.
The EIP-8037 issue is separate from the deposit-handling flaw, although both affect the upcoming Glamsterdam upgrade.
Glamsterdam was activated on the Sepolia testnet on October 6, allowing developers to examine changes to block construction and increased transaction-processing capacity. However, a new activation date for Hoodi has not been confirmed, and there is no confirmed mainnet activation date.
The deposit fix includes tests covering how deposits should be classified during the Gloas transition. Ethereum client teams must now incorporate the updated rules into their software and complete further testing before the correction can be used in a future network upgrade.