CVE-2021-42766: Proof-Of-Stake Ethereum Project Proof-Of-Stake Ethereum

Critical severity, CVSS 9.1. EPSS: 1% chance of exploitation in the next 30 days.

The Proof-of-Stake (PoS) Ethereum consensus protocol through 2021-10-19 allows an adversary to cause a denial of service (long-range consensus chain reorganizations), even when this adversary has little stake and cannot influence network message propagation. This can cause a protocol stall, or an increase in the profits of individual validators.

Affected products

• Proof-Of-Stake Ethereum Project Proof-Of-Stake Ethereum: up to and including 2021-10-19

Published 2021-10-20. Last modified 2026-06-17.