Babylon Nil BlockHash in BLS vote extensions triggers panics in consensus handlers

Exploitation

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

CVSS 4.0

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

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Summary A vulnerability exists in Babylon’s BLS vote extension processing where a malicious active validator can submit a VoteExtension with the blockhash field omitted from the protobuf serialization. Because protobuf fields are optional, unmarshalling succeeds but leaves BlockHash as nil. Babylon then dereferences this nil pointer in consensus-critical code paths (notably VerifyVoteExtension, and also proposal-time vote verification), causing a runtime panic. Impact Intermittent validator crashes at epoch boundaries, which would slow down the creation of the epoch boundary block. Finder Vulnerability discovered by: - @GrumpyLaurie55348

Published by the source

8 Dec 2025, 22:20 UTC

Last modified by the source

8 Dec 2025, 22:20 UTC

Source last checked

26 Oct 2026, 15:13 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-m6wq-66p2-c8pc

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# Patch Next advisory brief: GHSA-m6wq-66p2-c8pc

Advisory: Babylon Nil BlockHash in BLS vote extensions triggers panics in consensus handlers
IDs: GHSA-m6wq-66p2-c8pc
Record: https://patchnext.com/advisories/ghsa-m6wq-66p2-c8pc (revision 1, source checked 26 Oct 2026, 15:13 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: github.com/babylonlabs-io/babylon/v4 4.2.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/babylonlabs-io/babylon/v3: affected <= 3.0.0-snapshot.250805a
- Go github.com/babylonlabs-io/babylon/v4: affected < 4.2.0; fixed in 4.2.0
- Go github.com/babylonlabs-io/babylon/v2: affected <= 2.3.2
- Go github.com/babylonlabs-io/babylon: affected <= 1.1.0

## Suggested inspection (read-only)
- Go github.com/babylonlabs-io/babylon/v3: check the installed version with your package manager.
- Go github.com/babylonlabs-io/babylon/v4: check the installed version with your package manager.
- Go github.com/babylonlabs-io/babylon/v2: check the installed version with your package manager.
- Go github.com/babylonlabs-io/babylon: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/babylonlabs-io/babylon/v3, github.com/babylonlabs-io/babylon/v4, github.com/babylonlabs-io/babylon/v2, github.com/babylonlabs-io/babylon.
- 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-m6wq-66p2-c8pc (GitHub-reviewed advisory GHSA-m6wq-66p2-c8pc lists affected ranges: Go github.com/babylonlabs-io/babylon/v4 >=0 =0 =0 =0 <=1.1.0)

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