According to CoinMeta, one of Ethereum's consensus clients has merged a patch that fixes an attack targeting the verification node public key cache poisoning. This patch addresses a vulnerability related to the Gloas fork, which could cause some nodes to reject valid signatures due to errors in the global public key cache. Gloas is part of the consensus layer that will be upgraded with the upcoming Glamsterdam. Attackers need to have three pending deposits before the fork; the specific mechanism is quite complex. The fix involves adding public keys to the global cache only after the activation qualifications are finally determined.