Summary
Babylon Finality Provider MsgCommitPubRandList replay attack
A high vulnerability exists in the Babylon protocol's x/finality module due to a lack of domain separation in signed messages, combined with insufficient validation in the MsgCommitPubRandList handler. Specifically, the handler does not enforce that the submitted Commitment field is 32 bytes long. This allows an attacker to replay a signature originally generated for a different message (e.g., a Proof-of-Possession in MsgCreateFinalityProvider) as a MsgCommitPubRandList. By crafting the message parameters, an attacker can use the typically 20-byte address bytes (from the PoP context) to form the StartHeight, NumPubRand, and a shorter-than-expected Commitment (e.g., 4 bytes). The replayed signature will pass verification for this crafted message, leading to the injection of an invalid PubRand commitment.
Future recommendations
To minimize future risk of such attacks, all finality providers should:
- Never re-use your finality provider EOTS across the networks (e.g., the testnet) or for any other purpose.
- Never use EOTS keys to sign any other data than relevant to in-protocol messages. Ideally EOTS key should only be used to:
- Sign initial proof of possession message
- Sign periodic randomness commits
- Sign finality votes with every block
Finder
Vulnerability discovered by:
- Marco Hextor
- https://x.com/marcohextor
- @marcohextor
Impact
Successful exploitation of this vulnerability, specifically via the PoP signature replay, allows an attacker to store an invalid PubRand commitment (with a non-standard length, e.g., 4 bytes) for a targeted Finality Provider (FP). Despite the commitment itself being malformed, it's the associated StartHeight and NumPubRand (derived from the replayed address bytes and typically very large) that cause severe consequences
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.
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Frequently Asked Questions
- What is GHSA-7MM3-VFG8-7RG6? GHSA-7MM3-VFG8-7RG6 is a high-severity security vulnerability in github.com/babylonlabs-io/babylon (go), affecting versions < 1.1.0. It is fixed in 1.1.0.
- Which versions of github.com/babylonlabs-io/babylon are affected by GHSA-7MM3-VFG8-7RG6? github.com/babylonlabs-io/babylon (go) versions < 1.1.0 is affected.
- Is there a fix for GHSA-7MM3-VFG8-7RG6? Yes. GHSA-7MM3-VFG8-7RG6 is fixed in 1.1.0. Upgrade to this version or later.
- Is GHSA-7MM3-VFG8-7RG6 exploitable, and should I be worried? Whether GHSA-7MM3-VFG8-7RG6 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-7MM3-VFG8-7RG6 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-7MM3-VFG8-7RG6? Upgrade
github.com/babylonlabs-io/babylonto 1.1.0 or later.