CVE-2020-26241

Name: CVE-2020-26241
Creator: NVD / NIST
Published: 2020-11-25T02:15:11.047+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.1/10EPSS 1.08%

Last modified Jun 17, 2026

CVE-2020-26241 is a high-severity vulnerability rated 7.1/10 on the CVSS scale. 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. EPSS estimates a 1.08% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

7.1/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L

EPSS Probability

1.08%

60.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-682

Affected Software

Vendor	Product	Versions
Ethereum	Go Ethereum	< 1.9.17

References

https://blog.ethereum.org/2020/11/12/geth_security_release/Vendor Advisory
https://github.com/ethereum/go-ethereum/security/advisories/GHSA-69v6-xc2j-r2jfThird Party Advisory
https://blog.ethereum.org/2020/11/12/geth_security_release/Vendor Advisory
https://github.com/ethereum/go-ethereum/security/advisories/GHSA-69v6-xc2j-r2jfThird Party Advisory

Timeline

Published: Nov 25, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-26241?

How severe is CVE-2020-26241?

CVE-2020-26241 has a CVSS score of 7.1/10 (HIGH severity). The EPSS model estimates a 1.08% probability of exploitation in the next 30 days.

How do I fix CVE-2020-26241?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-26241?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST