Lido Engineer Flags Ethereum Hard Fork Vulnerability
A staking deposit vulnerability was identified ahead of the upcoming Glamsterdam network upgrade.
Updated on Oct. 20, 2026 in Cybersecurity
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Lido Finance engineer Dima Gusakov discovered a potential front-running attack risk targeting delegated staking protocols during the Ethereum Glamsterdam hard fork. Malicious node operators could exploit shared deposit queues to claim funds intended for staker validators.
Why it matters
The security gap highlights risks inherent in shared deposit queues during network transitions, prompting scrutiny of how builder deposits are handled. While Lido maintains its own security modules, the rejection of a fix by Ethereum maintainers leaves the issue open.
The potential exploit involves builder deposits using the 0xB0 prefix, which allows attackers to preemptively claim ETH intended for staker validators. This vulnerability is associated with Ethereum consensus-specs GitHub issue #5735.
The players
Dima Gusakov
He is an engineer at Lido Finance who specializes in identifying security risks within staking protocols.
Lido Finance
This is a liquid staking solution for Ethereum that allows users to earn rewards on their tokens while maintaining liquidity.
The details
The flaw exists in the pre-fork phase where both builder and validator deposits utilize a single shared queue. Node operators can leverage this overlap to claim staked assets before they reach the intended staker validators.
Timeline
2021: Lido experienced previous deposit front-running issues.
October 20, 2026: Dima Gusakov publicly identified the current attack risk.
October 26, 2026: The Glamsterdam hard fork is set to activate on the Hoodi testnet.
Q4 2026: Targeted timeframe for the official Glamsterdam mainnet launch.
The Tech Race
This vulnerability underscores the ongoing challenge of maintaining security as Ethereum transitions through complex hard fork upgrades. It highlights the tension between proposing defensive code updates and the protocol maintenance priorities set by the Ethereum consensus-specs GitHub repository.
Stakers relying on delegated protocols should monitor how their platforms mitigate front-running risks during the upcoming fork transition. Users should remain aware that automated security guards may be necessary to protect deposits while core protocol patches remain unimplemented.
The takeaway
Security research remains vital as blockchain protocols continue to undergo significant network upgrades. Stakeholders should prioritize platforms that maintain independent deposit security modules to hedge against protocol-level vulnerabilities.
What happens next
The Glamsterdam hard fork is scheduled to activate on the Hoodi testnet on October 26, 2026, ahead of a planned mainnet launch in Q4 2026.
Further reading
For more information on protocol protection, visit the Cybersecurity section.
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