Lido engineer warns of Glamsterdam staking deposit hijacking risk

Dmitry Gusakov, the engineering lead of the Ethereum liquid staking protocol Lido, warned at the developer conference ACDC #189 that the one-time builder access mechanism introduced by the Glamsterdam upgrade could interfere with the existing deposit protection logic of the staking protocol, leading to the hijacking of staking deposits. This issue involves multiple deposits sharing the same validator public key.

According to Ethereum's current deposit rules, the first valid deposit determines the withdrawal credential, and staking protocols typically leverage this feature to prevent credential manipulation, such as initially depositing a small amount of ETH and then topping up the remaining funds once the expected credential appears. However, the special access mechanism introduced for builders by Glamsterdam may change the interpretation of subsequent pending deposits under the same public key during the fork transition period, putting the staking protocol at risk of a third outcome: the validator does not appear, and the deposited ETH is credited to the builder.

Lido's proposed fix is to maintain the distinction between validator deposits and builder deposits during the one-time access process. However, core developers rejected this modification on the grounds of timing, mainly because the Sepolia testnet has already been activated according to existing specifications, and the Hoodi client version is also in preparation. Changing the behavior at this point could require redeploying Sepolia and conducting additional testing. The issue affects the access process during the fork transition period, rather than the ongoing deposit processing rules, but its consequences could impact deposits waiting in the queue.