CometBFT's default for BlockParams.MaxBytes consensus parameter may increase block times and affect consensus participation

Exploitation

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

CVSS

not scored

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Amulet Security Advisory for CometBFT: ASA-2023-002 Component: CometBFT Criticality: Low Affected versions: All Affected users: Validators, Chain Builders + Maintainers Summary A default configuration in CometBFT has been found to be large for common use cases, and may affect block times and consensus participation when fully utilized by chain participants. It is advised that chains consider their specific needs for their use case when setting the BlockParams.MaxBytes consensus parameter. Chains are encouraged to evaluate the impact of having proposed blocks with the maximum allowed block size, especially on bandwidth usage and block latency. Additionally, the timeoutpropose parameter should be computed using the maximum allowed block size as a reference. This issue does not represent an actively exploitable vulnerability that would result in a direct loss of funds, however it may have a slight impact on block latency depending on a network’s topography. When setting a large…

Published by the source

29 Sep 2023, 20:38 UTC

Last modified by the source

7 Apr 2024, 05:00 UTC

Source last checked

26 Oct 2026, 15:03 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-hq58-p9mv-338c

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# Patch Next advisory brief: GHSA-hq58-p9mv-338c

Advisory: CometBFT's default for `BlockParams.MaxBytes` consensus parameter may increase block times and affect consensus participation
IDs: GHSA-hq58-p9mv-338c
Record: https://patchnext.com/advisories/ghsa-hq58-p9mv-338c (revision 1, source checked 26 Oct 2026, 15:03 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/cometbft/cometbft 0.38.6, 0.37.5, 0.34.32. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/cometbft/cometbft: affected >= 0.38.0, < 0.38.6; >= 0.37.0, < 0.37.5; < 0.34.32; fixed in 0.37.5, 0.38.6, 0.34.32

## Suggested inspection (read-only)
- Go github.com/cometbft/cometbft: 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/cometbft/cometbft.
- 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-hq58-p9mv-338c (GitHub-reviewed advisory GHSA-hq58-p9mv-338c lists affected ranges: Go github.com/cometbft/cometbft >=0.38.0 =0.37.0 =0 <0.34.32)

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