The Ethereum Foundation has alerted validators and node operators to a live issue affecting the Prysm consensus client on Ethereum mainnet and has urged Prysm users to change their configuration to avoid unexpected behavior.
Ethereum Foundation Warns Prysm users
The alert states that Prysm-based consensus layer nodes on mainnet encounter a client-side problem that can affect how they process network data and attestations. Operators who run Prysm must reconfigure their consensus layer (CL) nodes according to updated guidance, while those using other consensus clients do not need to take any action.​
The notice arrives soon after Ethereum’s recent Fulu/Osaka upgrade, which increased data-handling demands on consensus clients and raised the operational complexity of running validators. The Foundation frames the Prysm issue as a technical configuration problem, and it emphasizes that the rest of the client ecosystem continues to operate normally.
Technical Risk Affecting Validators
Prysm developers and community alerts describe a bug that can make nodes process outdated attestations in a way that generates old or incorrect states, which in turn can degrade validator performance. If operators ignore the warning, their Prysm nodes may miss attestations or fall behind peers, increasing the risk of reduced rewards and contributing to localized instability in the client’s share of the network.​
Prysm remains one of Ethereum’s largest consensus clients, with estimates around one-fifth of the validator set relying on the software, so misconfigurations can create network-level pressure even if other clients stay healthy. Researchers previously linked similar “valid-but-old attestation” handling issues to higher CPU load and connectivity problems during past finality incidents, which led to missed slots and weaker participation from affected validators.
Prysm maintainers recommend that validators add a specific safety flag to their beacon node configuration and restart their nodes so that they stop generating outdated states when they encounter old attestations. The workaround applies to current Prysm releases on mainnet and does not require users to rotate keys, perform a full resync or shut down validators, which keeps operators’ downtime and operational risk low.
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