An earlier security incident involving MetaMask validators may have resulted from tampering with block-reward fee recipient addresses, Kaden said. Of 19 MetaMask validators that received block rewards, 18 did not send them to the correct fee recipient address and instead transferred them to 0x98B9...24A3, an address supported by Tornado Cash (a crypto-mixing protocol). The attacker stole about 0.36 ETH and, based on current information, may not have been able to withdraw staked ETH. About 17,000 validators have voluntarily exited, involving roughly 523,000 ETH. Kaden said it remains unclear whether the attacker could modify all fee recipient addresses.