Summary
Babylon Nil BlockHash in BLS vote extensions triggers panics in consensus handlers
A vulnerability exists in Babylon’s BLS vote extension processing where a malicious active validator can submit a VoteExtension with the block_hash 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.
Finder
Vulnerability discovered by:
- @GrumpyLaurie55348
Impact
Intermittent validator crashes at epoch boundaries, which would slow down the creation of the epoch boundary block.
The application dereferences a null pointer, causing a crash. Typical impact: denial of service via crash.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is GHSA-M6WQ-66P2-C8PC? GHSA-M6WQ-66P2-C8PC is a high-severity null pointer dereference vulnerability in github.com/babylonlabs-io/babylon/v4 (go), affecting versions < 4.2.0. It is fixed in 4.2.0. The application dereferences a null pointer, causing a crash.
- Which packages are affected by GHSA-M6WQ-66P2-C8PC?
github.com/babylonlabs-io/babylon/v4(go) (versions < 4.2.0)github.com/babylonlabs-io/babylon/v3(go) (versions <= 3.0.0-snapshot.250805a)github.com/babylonlabs-io/babylon/v2(go) (versions <= 2.3.2)github.com/babylonlabs-io/babylon(go) (versions <= 1.1.0)
- Is there a fix for GHSA-M6WQ-66P2-C8PC? Yes. GHSA-M6WQ-66P2-C8PC is fixed in 4.2.0. Upgrade to this version or later.
- Is GHSA-M6WQ-66P2-C8PC exploitable, and should I be worried? Whether GHSA-M6WQ-66P2-C8PC is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-M6WQ-66P2-C8PC is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-M6WQ-66P2-C8PC? Upgrade
github.com/babylonlabs-io/babylon/v4to 4.2.0 or later.