Consensus flaw during block processing in github.com/ethereum/go-ethereum

Exploitation

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

CVSS

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

EPSS

• CVE-2020-26265: 0.92% estimated exploitation activity in the next 30 days; percentile 60.32 (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 consensus-vulnerability in Geth could cause a chain split, where vulnerable versions refuse to accept the canonical chain. Description A flaw was repoted at 2020-08-11 by John Youngseok Yang (Software Platform Lab), where a particular sequence of transactions could cause a consensus failure. - Tx 1: - sender invokes caller. - caller invokes 0xaa. 0xaa has 3 wei, does a self-destruct-to-self - caller does a 1 wei -call to 0xaa, who thereby has 1 wei (the code in 0xaa still executed, since the tx is still ongoing, but doesn't redo the selfdestruct, it takes a different path if callvalue is non-zero) - Tx 2: - sender does a 5-wei call to 0xaa. No exec (since no code). In geth, the result would be that 0xaa had 6 wei, whereas OE reported (correctly) 5 wei. Furthermore, in geth, if the second tx was not executed, the 0xaa would be destructed, resulting in 0 wei. Thus obviously wrong. It was determined that the root cause was this commit from this PR. The semantics of createObject…

Published by the source

29 Jun 2021, 21:14 UTC

Last modified by the source

14 Feb 2023, 20:54 UTC

Source last checked

26 Oct 2026, 14:55 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-xw37-57qp-9mm4

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# Patch Next advisory brief: CVE-2020-26265

Advisory: Consensus flaw during block processing in github.com/ethereum/go-ethereum
IDs: CVE-2020-26265, GHSA-xw37-57qp-9mm4
Record: https://patchnext.com/advisories/cve-2020-26265 (revision 1, source checked 26 Oct 2026, 14:55 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
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 1.9.20. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/ethereum/go-ethereum: affected >= 1.9.4, < 1.9.20; fixed in 1.9.20

## 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-xw37-57qp-9mm4 (GitHub-reviewed advisory GHSA-xw37-57qp-9mm4 lists affected ranges: Go github.com/ethereum/go-ethereum >=1.9.4 <1.9.20)

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