Фиаско Fusaka: Валидаторы Ethereum потеряли 25% активности из-за сбоя в Prysm Translation: Fusaka Fiasco: Ethereum Validators Lose 25% Activity Due to Prysm Bug

Shortly after the deployment of Fusaka, a failure occurred within the popular consensus client Prysm, affecting a portion of Ethereum validators.

A bug was identified in client version v7.0.0, which caused outdated blockchain states to be generated unnecessarily when processing old confirmations.

As explained by lead developer Terence Cao, this issue disrupted the proper functioning of nodes utilizing this client. Specialists provided a temporary workaround to disable the faulty feature.

Despite these measures, during epoch 411,448, key network metrics still saw a significant drop. Only 75% of the nodes were signing the latest block headers, while consensus participation plummeted to 74.7%. Ethereum was on the brink of a full-scale failure, as less than nine percentage points remained before block finalization would cease altogether.

As of now (epoch 411,760), the network’s performance has returned to normal. Metrics have nearly rebounded to pre-crisis levels:

Before the incident, these figures consistently exceeded 99%.

The decline in consensus participation roughly matches the proportion of validators using the Prysm client. On December 3, it was 22.71%, but it currently stands at 15.65%.

According to Ethereum’s consensus rules, the network risks losing finalization if validator voting participation falls below a critical threshold—two-thirds of the staked Ether.

In such a scenario, new blocks are still generated, but the chain ceases to be irreversibly confirmed, significantly increasing the risk of transaction history reorganization. A loss of finalization could trigger a cascading failure across the entire ecosystem. Potential ramifications could include:

This scenario is not hypothetical. In May 2023, Ethereum faced finalization failures—twice in a single day. At that time, the errors were attributed to data processing issues in the Prysm and Teku clients.

The current incident appeared relatively localized, but historically, the risk has been much higher. In the fall of 2021, Prysm controlled over 66% of the nodes—meaning that an error within it alone could have paralyzed the entire network.

By January 2022, its share had risen to 68.1%, leaving the network in a vulnerable position.

Despite some progress, Ethereum remains far from achieving a safe distribution of clients. A critical threshold is considered to be 33% for any single client. Lighthouse currently dominates the market with a share of 52.55%.

“We only narrowly avoided catastrophe. If the bug had occurred in Lighthouse, the network could have lost finalization,” commented Ethereum expert Anthony Sassano.

As a reminder, a failure occurred in early September with the execution client Reth from Paradigm. The bug halted the synchronization of nodes using this software.