Following a security breach that hijacked reward payouts, MetaMask is pulling thousands of Ethereum validators, which has triggered a network-wide queue for stakers attempting to leave.
Onchain security researcher Kaden reported that approximately 17,000 MetaMask-administered validators, representing around 523,000 ETH, were proactively pulled after an investigation revealed transaction-fee rewards from 18 out of 19 block-proposing validators were redirected to an address funded via Tornado Cash, an Ethereum privacy mixer that anonymizes cryptocurrency transactions.
Kaden estimates the attacker successfully captured a mere 0.36 ETH. However, the more pressing worry centers on how the perpetrator obtained enough access to modify fee recipients and whether that access reached validator signing keys, an exposure that could cause slashable offenses.
While MetaMask has not verified these numbers or revealed the root cause, the firm stated that a segment of its infrastructure was breached, prompting it to pull impacted validators defensively while collaborating with clients, partners, and security experts. The company added that MetaMask wallets face no immediate danger.
MetaMask also emphasized that its staking service operates on a non-custodial basis and that it lacks control over clients’ withdrawal keys. This boundary stops an attacker possessing only validator-level access from withdrawing the underlying stake, though it does not rule out penalties if signing keys were breached and exploited.
According to Kaden, 821 potentially vulnerable validators have not yet been pulled, which includes three belonging to the group whose fee rewards were allegedly rerouted. It remains unconfirmed why these validators remain active or if the attacker still has access to alter more fee recipients.
MetaMask has yet to clarify the total number of impacted validators, whether signing keys were compromised, or if any slashing has taken place.
Ethereum’s withdrawal backlog spikes to 9-month high
In the wake of the breach, the resulting exits are already impacting Ethereum’s broader staking architecture.
Validator Queue figures show that roughly 773,447 ETH was queued for exit on Wednesday, pointing to a wait time of 13 days and 10 hours before an exiting validator clears the line. An extra withdrawal sweep delay was projected at 7.6 days.
Historical data from Validator Queue indicates this is the most substantial exit backlog since December 2025, surpassing the approximately 476,000 ETH pending during a previous spike in May.
This bottleneck is the result of a native Ethereum safeguard rather than a failure in processing capability.
To stop sudden shifts from undermining its proof-of-stake consensus, Ethereum restricts how fast stake can join or leave the validator network. Data from the Validator Queue indicated a churn rate of 256 ETH per epoch, with each epoch spanning roughly 6.4 minutes. Consequently, a massive wave of exits must be cleared incrementally instead of all at once.
The extra 7.6-day sweep window kicks off once validators finish the exit queue and transition to a withdrawable status. Ethereum then loops through qualified validators to send balances to their designated withdrawal addresses.
The disruption may persist even longer for stake tied to MetaMask. Lido—where MetaMask runs validators—projects that the complete cycle of exiting, withdrawing, and eventually re-entering could stretch up to 45 days, compounded by a separate 27-day entry queue that returning validators must also wait through.