# CVE-2020-26264: LES Server DoS via GetProofsV2

> A malicious request can crash the Light Ethereum Subprotocol server, requiring users to upgrade or disable the feature.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Dec 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-r33q-22hv-j29q, GO-2021-0063

## What is CVE-2020-26264?

CVE-2020-26264 is a medium-severity denial of service vulnerability in go-ethereum, published on 11 Dec 2020. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Go Ethereum, or "Geth", is the official Golang implementation of the Ethereum protocol. In Geth before version 1.9.25 a denial-of-service vulnerability can make a LES server crash via malicious GetProofsV2 request from a connected LES client. This vulnerability only concerns users explicitly enabling les server; disabling les prevents the exploit. The vulnerability was patched in version 1.9.25.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2020-26264?

3 open source packages ship an affected version, including github.com/ethereum/go-ethereum. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/ethereum/go-ethereum` | Go | All versions | 1.9.25 |
| `github.com/ethereum/go-ethereum` | Go | All versions | 1.9.25 |
| `github.com/ethereum/go-ethereum` | Go | All versions | 1.9.25 |

Products: Ethereum Go Ethereum.

## How do I fix CVE-2020-26264?

Upgrade github.com/ethereum/go-ethereum to 1.9.25 or later.

## Is CVE-2020-26264 being exploited?

There is no known exploitation of CVE-2020-26264 in the wild and no public exploit code.

## Other vulnerabilities in go-ethereum

- [CVE-2026-26314](https://insights.sbomify.com/CVE-2026-26314/): Go Ethereum affected by DoS via malicious p2p message (high 8.7)
- [CVE-2023-42319](https://insights.sbomify.com/CVE-2023-42319/): go-ethereum vulnerable to denial of service via crafted GraphQL query (high 7.5)
- [CVE-2023-40591](https://insights.sbomify.com/CVE-2023-40591/): Denial of service via malicious p2p message in go-ethereum (high 7.5)
- [CVE-2021-42219](https://insights.sbomify.com/CVE-2021-42219/): Denial of service in go-ethereum (high 7.5)
- [CVE-2022-23327](https://insights.sbomify.com/CVE-2022-23327/): Denial of Service in Go-Ethereum (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-26264 and fix it if it is affected.

What it is: CVE-2020-26264 is a medium-severity denial of service vulnerability in go-ethereum, published on 11 Dec 2020. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2020-26264 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/ethereum/go-ethereum (Go): affected all versions; fixed in 1.9.25
- github.com/ethereum/go-ethereum (Go): affected all versions; fixed in 1.9.25
- github.com/ethereum/go-ethereum (Go): affected all versions; fixed in 1.9.25

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2020-26264/ (Markdown: https://insights.sbomify.com/CVE-2020-26264/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-26264
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-26264
- OSV: https://osv.dev/vulnerability/CVE-2020-26264

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-26264/
Summaries are generated and may contain mistakes; the official description above is the record.