Ethereum Glamsterdam mainnet upgrade

Glamsterdam, a combined consensus-layer and execution-layer hard fork for Ethereum, is targeted for mainnet launch in Q4 2026 (October to December). No mainnet date has been set, so the timing remains tentative. The upgrade concerns ETH and the validators and staking protocols built around it.

What is happening

Glamsterdam is the combined name for two sets of changes: Gloas covers the consensus layer, while Amsterdam handles the execution layer. Among its changes is a new type of builder deposit that uses withdrawal credentials marked with the 0xB0 prefix. Withdrawal credentials tell the network who owns staked ETH and where it ultimately goes.

The upgrade is scheduled to activate on the Hoodi testnet on October 26, 2026. A mainnet date has not yet been announced, and the Q4 2026 window is a target rather than a confirmed schedule.

On October 20, 2026, Dima Gusakov, Head of Engineering at Lido Finance, flagged a possible front-running attack tied to the transition. According to his warning, builder deposits and validator deposits will share deposit queues around the fork. A malicious node operator with the right access could submit a builder deposit that claims ETH intended for a staker's validator. In that case the deposit would be credited to the attacker's builder account and the intended validator would never activate. The issue is limited to the pre-fork phase and is not described as a permanent flaw in Ethereum's design.

The concern was raised in the Ethereum consensus-specs repository as issue #5735, which proposed pre-deposit checks. The issue was closed as "not planned," leaving the defense to staking protocols rather than the core specification.

Why it matters

Glamsterdam is a major network upgrade for Ethereum, and any hard fork affects node operators, validators and staking providers. The reported risk concerns delegated staking and liquid staking protocols, which depend on deposits being routed correctly. Holders who stake through such services may want to check how their provider handles deposit verification around the fork.

Lido already runs a Deposit Security Module with a guardian committee, built after deposit front-running vulnerabilities came to light in 2021. The open question is whether that setup, and equivalents at other providers, accounts for the 0xB0 credentials and the shared queues at the fork boundary. Providers without comparable checks may need to act before mainnet activation. For traders and holders, the Hoodi testnet activation and any announcement of a mainnet date are the main milestones to follow.

Key details

• Date: Q4 2026 (October 1 - December 31, 2026); exact mainnet date not set; Hoodi testnet activation scheduled for October 26, 2026
• Project: Ethereum
• Coins: ETH
• Category: Network Upgrade
• Status: Tentative
• Source: https://cryptobriefing.com/lido-engineer-glamsterdam-staking-deposit-risk/