Prysm Bug After Fusaka Upgrade Costs Ethereum Validators Over $1M
Prysm, one of Ethereum's primary consensus clients, reported that validators collectively lost 382 ETH—worth over $1 million—after a software bug triggered network disruptions shortly following the Fusaka upgrade on Dec. 14, 2025. The problem caused missed attestations and resulting penalties for affected validators, reducing staking rewards and forcing node operators to troubleshoot during a critical upgrade window.
The incident underscores the operational risks tied to client software during protocol rollouts and highlights why client diversity and rapid fixes matter for network resilience. Prysm has reported the losses, and the community is awaiting more technical details and remediation guidance from the client team. Validator operators, staking providers, and exchanges will likely review monitoring and upgrade practices to limit similar losses as the network stabilizes.