Go Ethereum, or “Geth”, is the official Golang implementation of the Ethereum protocol. This is a Consensus vulnerability in Geth before version 1.9.17 which can be used to cause a chain-split where vulnerable nodes reject the canonical chain. Geth’s pre-compiled dataCopy (at 0x00 04) contract did a shallow copy on invocation. An attacker could deploy a contract that writes X to an EVM memory region R, then calls 0x00 04 with R as an argument, then overwrites R to Y, and finally invokes the RETURNDATACOPY opcode. When this contract is invoked, a consensus-compliant node would push X on the EVM stack, whereas Geth would push Y. This is fixed in version 1.9.17.
Source: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26241
Reference (s):
- https://github.com/ethereum/go-ethereum/security/advisories/GHSA-69v6-xc2j-r2jf
- URL: https://github.com/ethereum/go-ethereum/security/advisories/GHSA-69v6-xc2j-r2jf
- https://blog.ethereum.org/2020/11/12/geth_security_release/
- URL: https://blog.ethereum.org/2020/11/12/geth_security_release/