CVE-2020-26242: Denial of Service in go-ethereum
Summary
CVE-2020-26242: Denial of service in geth. Affects github.com/ethereum/go-ethereum versions >= 1.9.16, < 1.9.18. Fixed in 1.9.18. How to fix ↓
Also tracked for
The same CVE-2020-26242 is tracked separately for each ecosystem and vendor. Its fix information is the same; the package and affected versions differ.
Check if this vulnerability affects your application
Upload a manifest or SBOM and we'll show whether you're affected, plus every other risky package in the same scan.
No signup required · Results in about 60 seconds
Background
go-ethereum is an open-source project that provides the Go implementation of the Ethereum protocol. It is widely used as a client for interacting with the Ethereum network. The vulnerability identified as CVE-2020-26242 affects go-ethereum versions prior to v1.9.18. This vulnerability can lead to a denial-of-service (crash) during block processing.
Vulnerability Detail
The vulnerability arises from a flaw in the MULMOD operation of the uint256 library, which is utilized by go-ethereum. By specifying a modulo of 0 in the mulmod(a,b,0) operation, an attacker can trigger a panic in the library. This panic occurs due to a buffer underflow in the uint256 library, where the dLen variable remains 0 if d is equal to 0. As a result, an attempt to access index [-1] is made, leading to a crash. Exploiting this vulnerability can cause all vulnerable nodes to drop off the network.
How To Fix
Latest published version: v1.17.9 as of 23 Oct 2026
go get github.com/ethereum/go-ethereum@v1.17.9Upgrading to it may include breaking changes; the version below is the minimum fixed release for this vulnerability.
If you need the minimum change
1.9.18
This is the first release that contains the fix.
go get github.com/ethereum/go-ethereum@v1.9.18Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
There is no known workaround for this vulnerability. It is essential to upgrade to the patched version of go-ethereum to mitigate the risk.
Conclusion
The CVE-2020-26242 vulnerability in go-ethereum can result in a denial-of-service condition during block processing. Upgrading to go-ethereum v1.9.18 or higher is crucial to mitigate this risk. No workarounds are available, and it is recommended to apply the patch as soon as possible. For further support on vulnerability remediation, please contact DevNack.com.
See every vulnerability recorded for github.com/ethereum/go-ethereum →
FAQ
The vulnerability can lead to a denial-of-service (crash) during block processing, causing affected nodes to drop off the network.
You can use the Vulert Playground at Vulert Scanner to check if your application is affected by this vulnerability. It requires no signup and uses Gopkg.lock to monitor and alert in real-time for open-source vulnerabilities.
Yes, upgrading to go-ethereum v1.9.18 or higher will fix this vulnerability.
No, there are no known workarounds for this vulnerability. Upgrading to the patched version is necessary.
This vulnerability was discovered and reported by the Ethereum security team.
References
Related vulnerabilities
Recent vulnerabilities recorded for github.com/ethereum/go-ethereum.
