CometBFT has inconsistencies between how commit signatures are verified and how block time is derived

Exploitation

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

CVSS 4.0

7.1 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N · score source

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

CSA-2026-001: Tachyon Description Name: CSA-2026-001: Tachyon Criticality: Critical (Catastrophic Impact; Possible Likelihood per ACMv1.2) Affected versions: All versions of CometBFT Affected users: Validators and protocols relying on block timestamps Description A consensus-level vulnerability was discovered in CometBFT's "BFT Time" implementation due to an inconsistency between how commit signatures are verified and how block time is derived. This breaks a core BFT Time guarantee: "A faulty process cannot arbitrarily increase the Time value." Impact Downstream impact on chains affects any module, smart contract, or system that relies on the block timestamp. Patches The new CometBFT releases v0.38.21 and v0.37.18 fix this issue. The main unreleased branch is also patched. Workarounds There are no effective workarounds for this vulnerability. Upgrading to patched versions is required. Timeline - January 8, 2026, 5:27PM UTC: Issue reported to Cosmos Bug Bounty Program - January 9,…

Published by the source

23 Jan 2026, 16:56 UTC

Last modified by the source

27 Feb 2026, 21:37 UTC

Source last checked

26 Oct 2026, 15:14 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-c32p-wcqj-j677

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# Patch Next advisory brief: GHSA-c32p-wcqj-j677

Advisory: CometBFT has inconsistencies between how commit signatures are verified and how block time is derived
IDs: GHSA-c32p-wcqj-j677
Record: https://patchnext.com/advisories/ghsa-c32p-wcqj-j677 (revision 1, source checked 26 Oct 2026, 15:14 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.1)
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 0.38.21, 0.37.18. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/cometbft/cometbft: affected >= 0.38.0-alpha.1, <= 0.38.20; <= 0.37.17; fixed in 0.37.18, 0.38.21

## 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-c32p-wcqj-j677 (GitHub-reviewed advisory GHSA-c32p-wcqj-j677 lists affected ranges: Go github.com/cometbft/cometbft >=0.38.0-alpha.1 =0 <=0.37.17)

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