How severe is CVE-2020-26264?

CVE-2020-26264 has a CVSS score of 6.5/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2020-26264?

CVE-2020-26264 affects the following packages: github.com/ethereum/go-ethereum (Go). Ecosystems affected: Go.

How do I fix CVE-2020-26264?

Update github.com/ethereum/go-ethereum to 1.9.25 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-26264 is resolved across your whole dependency graph.

How do I detect CVE-2020-26264 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/ethereum/go-ethereum, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2020-26264 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2020-26264 actively exploited in the wild?

No public exploit code has been indexed for CVE-2020-26264 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2020-26264?

CVE-2020-26264 has an EPSS (Exploit Prediction Scoring System) score of 1.9%, placing it in the 79th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2020-26264?

CVE-2020-26264 is classified as Uncontrolled Resource Consumption (CWE-400). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2020-26264 published, and has it been updated?

CVE-2020-26264 was published on December 11, 2020 and was last updated on August 7, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹

🐹 Go

Not in CISA KEV

MEDIUM severity

CVE-2020-26264 — go-ethereum

MEDIUMFix: ethereum/go-ethereum@bddd103

CVE-2020-26264 is a medium-severity (CVSS 6.5) Uncontrolled Resource Consumption vulnerability in github.com/ethereum/go-ethereum. A fix is available for github.com/ethereum/go-ethereum — see the affected versions and patch details below.

Denial of service in github.com/ethereum/go-ethereum

Also known asGHSA-r33q-22hv-j29qGO-2021-0063

Published

Dec 11, 2020

Updated

Aug 7, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.9%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs79th percentile — riskier than 79% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2020-26264 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

🐹github.com/ethereum/go-ethereum

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Impact

A DoS vulnerability can make a LES server crash via malicious GetProofsV2 request from a connected LES client.

Patches

The vulnerability was patched in https://github.com/ethereum/go-ethereum/pull/21896.

Workarounds

This vulnerability only concerns users explicitly enabling les server; disabling les prevents the exploit. It can also be patched by manually applying the patch in https://github.com/ethereum/go-ethereum/pull/21896.

For more information

If you have any questions or comments about this advisory:

Open an issue in go-ethereum
Email us at [email protected]

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/ethereum/go-ethereum`	all versions	1.9.25`go get github.com/ethereum/go-ethereum@v1.9.25`

Affected Products

1 product · 1 configurations

Application

go ethereumethereum

< 1.9.25

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/ethereum/go-ethereum, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/ethereum/go-ethereum to 1.9.25 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-26264 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

### Impact A DoS vulnerability can make a LES server crash via malicious `GetProofsV2` request from a connected LES client. ### Patches The vulnerability was patched in https://github.com/ethereum/go-ethereum/pull/21896. ### Workarounds This vulnerability only concerns users explicitly enabling `les` server; disabling `les` prevents the exploit. It can also be patched by manually applying the patch in https://github.com/ethereum/go-ethereum/pull/21896. ### For more information If you have any questions or comments about this advisory: * Open an issue in [go-ethereum](https://github.c