Shallow copy bug in geth
CVE-2020-26241

6.5MEDIUM

Key Information:

Vendor

Ethereum

Status
Go-ethereum
Vendor
CVE Published:
25 November 2020

What is CVE-2020-26241?

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.

Affected Version(s)

go-ethereum >= 1.9.7, < 1.9.17

References

https://blog.ethereum.org/2020/11/12/geth_security_release/
x_refsource_MISC
https://github.com/ethereum/go-ethereum/security/advisori...
x_refsource_CONFIRM

CVSS V3.1

Score:
6.5
Severity:
MEDIUM
Confidentiality:
None
Integrity:
High
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.
CVE-2020-26241 : Shallow copy bug in geth