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Ethereum Contains Consensus Flaw During Block Processing

Moderate severity GitHub Reviewed Published Aug 24, 2021 in ethereum/go-ethereum • Updated Aug 29, 2023

Package

gomod github.com/ethereum/go-ethereum (Go)

Affected versions

>= 1.10.0, < 1.10.8

Patched versions

1.10.8

Description

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:

References

@holiman holiman published to ethereum/go-ethereum Aug 24, 2021
Published by the National Vulnerability Database Aug 24, 2021
Reviewed Aug 26, 2021
Published to the GitHub Advisory Database Aug 30, 2021
Last updated Aug 29, 2023

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS score

0.074%
(34th percentile)

Weaknesses

CVE ID

CVE-2021-39137

GHSA ID

GHSA-9856-9gg9-qcmq

Source code

Credits

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