MetaMask exits swell Ethereum validator queue to 9-month high

MetaMask is exiting roughly 17,000 validators that together hold about 523,000 ETH after a security breach diverted validator fee rewards. The withdrawals pushed Ethereum’s validator exit queue to about 773,447 ETH, the largest backlog since December 2025.

On-chain researcher Kaden reported that fee rewards from 18 of 19 validators that proposed blocks were redirected to an account funded through Tornado Cash. The researcher estimated the attacker captured roughly 0.36 ETH. The central technical concern is whether the attacker gained access to validator signing keys, which could permit slashable actions that reduce staked balances.

MetaMask confirmed part of its staking infrastructure was compromised and said it is proactively exiting affected validators while working with clients, partners and security advisers. The company stated it had found no immediate threat to MetaMask wallets and noted its staking operation is non-custodial: MetaMask does not hold clients’ withdrawal keys. That separation prevents withdrawal of staked ETH by an attacker who only controls validator-level access, but it would not stop penalties if signing keys were misused.

Validator queue data show about 773,447 ETH waiting to leave the validator set, which translates to an estimated 13 days and 10 hours before an exiting validator clears the queue at the current processing rate. Ethereum limits how quickly stake can enter or leave the validator set to avoid abrupt changes to its proof-of-stake consensus. The network’s churn rate is about 256 ETH per epoch, with each epoch lasting roughly 6.4 minutes. After a validator clears the exit queue, an additional withdrawal sweep delay of about 7.6 days applies before balances reach designated withdrawal addresses.

Liquidity providers and node operators that route validator exits through liquid-staking infrastructure may face longer disruptions. Lido estimates the full process of exit, withdrawal and any eventual re-entry could take up to 45 days for affected validators, in part because validators returning to the network must wait through an entry queue currently around 27 days long.

MetaMask has not publicly confirmed the exact number of affected validators or whether signing keys were exposed or if any slashing has occurred. Kaden also reported about 821 potentially affected validators had not yet exited, including three among those whose fee rewards were allegedly diverted; the researcher flagged uncertainty about why those validators remain active.

The diverted fee-recipient address drew attention because it was funded through Tornado Cash, a protocol that mixes transactions to increase anonymity. Changing a validator’s fee recipient can redirect proposer fee rewards. The main risk for stakers and operators is loss of signing-key security, which can enable slashable behavior.

Security researchers and node operators are monitoring the exit queue and related logs. Because protocol limits fix the pace of exits and entries, large precautionary withdrawals create multi-week delays for affected validators and for staking infrastructure that processes those validators.