Ethereum Contains Consensus Flaw During Block Processing

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2021-39137: 1.32% estimated exploitation activity in the next 30 days; percentile 70.99 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact A vulnerability in the Geth EVM could cause a node to reject the canonical chain. Description A memory-corruption bug within the EVM can cause a consensus error, where vulnerable nodes obtain a different stateRoot when processing a maliciously crafted transaction. This, in turn, would lead to the chain being split in two forks. All Geth versions supporting the London hard fork are vulnerable (which predates London), so all users should update. This bug was exploited on Mainnet at block 13107518, leading to a minority chain split. Patches A patch is included in the v1.10.8 release. The exact patch to fix the issue is contained within this commit Workarounds No workarounds exist, save to update and/or apply the patch commit. References. Post-mortem write-up. Credits The bug was found by @guidovranken (working for Sentnl during an audit of the Telos EVM) and reported via bounty@ethereum.org. For more information If you have any questions or comments about this advisory: Open an…

Published by the source

30 Aug 2021, 16:15 UTC

Last modified by the source

29 Aug 2023, 18:53 UTC

Source last checked

26 Oct 2026, 14:58 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-9856-9gg9-qcmq

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# Patch Next advisory brief: CVE-2021-39137

Advisory: Ethereum Contains Consensus Flaw During Block Processing
IDs: CVE-2021-39137, GHSA-9856-9gg9-qcmq
Record: https://patchnext.com/advisories/cve-2021-39137 (revision 1, source checked 26 Oct 2026, 14:58 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/ethereum/go-ethereum 1.10.8. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/ethereum/go-ethereum: affected >= 1.10.0, < 1.10.8; fixed in 1.10.8

## Suggested inspection (read-only)
- Go github.com/ethereum/go-ethereum: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/ethereum/go-ethereum.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-9856-9gg9-qcmq (GitHub-reviewed advisory GHSA-9856-9gg9-qcmq lists affected ranges: Go github.com/ethereum/go-ethereum >=1.10.0 <1.10.8)

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