Ethereum validators have lost over $1 million owing to a Prysm bug, a software malfunction that saw 382 Ethereum depleted from the network, as per a BeinCrypto report.
The update comes after the Ethereum blockchain went through the Fusaka upgrade. The problem originally surfaced on December 4th, 2025, when an element was added to the testnet that would cause issues to the mainnet later on.
This disruption has created 41 missed epochs, 248 blocks, and 1,344 available slots—which created an 18.5% missed slot rate and a reduction of overall network participation of 75%.
Offchain Labs said the bug was introduced a month ago and, after being deployed, was triggered on the mainnet after the Fusaka upgrade.
“Prysm Beacon nodes received attestations from nodes that were possibly out of sync with the network. These attestations referenced a block root from the previous epoch,”
Prysm has said it has made permanent changes to its attestation validation logic to stop the situation from happening again.
Prysm is an important part of Ethereum’s framework. It is an open-source consensus client that is written in Go, allowing users to run nodes and take part in Ethereum’s decentralized networks via validation and staking. Offchain Labs is the developer behind Prysm.
While Prysm accounts for a fair portion of the Ethereum network, Offchain Labs said the effects could have been more severe if Prysm represented a large share of Ethereum’s validators.
“A client with more than 1/3rd of the network would have caused a temporary loss in finality and more missed blocks. A bug client with more than 2/3rd could finalize an invalid chain,”