GHSA-g5xx-c4hv-9ccc is a medium-severity (CVSS 4.7) vulnerability in github.com/cometbft/cometbft/light. A fix is available for github.com/cometbft/cometbft/light — see the affected versions and patch details below.
CometBFT's state syncing validator from malicious node may lead to a chain split
Real-World Exposure
github.com/cometbft/cometbft/light🐹github.com/cometbft/cometbft/light🐹github.com/cometbft/cometbft/light🐹github.com/cometbft/cometbft🐹github.com/cometbft/cometbftReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Name: ASA-2024-009: State syncing validator from malicious node may lead to a chain split Component: CometBFT Criticality: Medium (ACMv1.2: I:Moderate; L: Possible) Affected versions: >= 0.34.0, <= 0.34.33, >=0.37.0, <= 0.37.10, >= 0.38.0, <= 0.38.11
Summary
The state sync protocol retrieves a snapshot of the application and installs it in a fresh node. In order for this node to be ready to run consensus and block sync from the installed snapshot height, we also need to install a valid State in the node, which is the starting state from which it is able to validate new blocks and append them to the blockchain.
The State object used by state sync is computed using the light client protocol, which retrieves information about committed blocks from at least two RPC endpoints. The light client protocol performs several state validations and, in particular, compares the state provided by different RPC endpoints, looking for inconsistencies.
The State object contains, among other fields, a Validators field which stores the current validator set. A validator set is a list of validator addresses, public keys and associated voting powers, one per validator. It also stores, for historical reasons, the state of the proposer selection algorithm, in the form of the ProposerPriority field associated with each Validator.
While the light client is able to validate the ValidatorSet retrieved from RPC endpoints, this validation does not include the ProposerPriority field associated with each Validator. As a result, when state sync adopts RPC endpoints that, for unknown reasons, provide an invalid state of the proposer selection algorithm, the node will not be able to properly run the consensus protocol, as their local view of which validator is the proposer of a given round and height will disagree with the views of the correct validators. If an increasing number of validators state sync using RPC endpoints with invalid states, the network eventually halts.
Patches
Release versions 0.34.34, 0.37.11, and 0.38.12 include a patch to address this issue.
In the patched versions, the light client protocol compares the ProposerPriority fields of the ValidatorSet instances retrieved from the RPC endpoints configured for state sync. If they differ, the computed State object is considered invalid and state sync will fail with an error.
Workarounds
The issue is observed when validators run state sync using RPC nodes that are malicious or report invalid states for the proposer selection algorithm.
It is worth noting that non-malicious nodes running upstream software should never report an invalid state for the proposer selection algorithm. This situation may result from the adoption of nodes with customized code or which had their state, stored in local databases, manually updated.
When the network public's RPC endpoints have an invalid state for the proposer election algorithm, there, new validators should refrain from using state sync for bootstrapping or be sure that they configure for state sync RPC endpoints with a valid state of the proposer election algorithm.
A validator with an invalid state for the proposer selection algorithm will reject most of the proposed blocks and will have the network rejecting blocks it has proposed. It is also possible to manually compare the state of the proposer election algorithm of nodes by comparing the outputs of the /validators?height=_ RPC endpoints. The outputs must fully match, including the ProposerPriority field associated with each validator.
References
This issue was reported to the Cosmos Bug Bounty Program on HackerOne on 12/08/24. If you believe you have found a bug in the Interchain Stack or would like to contribute to the program by reporting a bug, please see https://hackerone.com/cosmos.
If you have questions about Interchain security efforts, please reach out to our official communication channel at [email protected].
For more information about CometBFT, please see https://docs.cometbft.com/.
For more information about the Interchain Foundation’s engagement with Amulet, please see https://github.com/interchainio/security.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/cometbft/cometbft/light | ≥ 0.34.0&&< 0.34.34 | 0.34.34go get github.com/cometbft/cometbft/light@v0.34.34 |
| 🐹Go | github.com/cometbft/cometbft/light | ≥ 0.37.0&&< 0.37.11 | 0.37.11go get github.com/cometbft/cometbft/light@v0.37.11 |
| 🐹Go | github.com/cometbft/cometbft/light | ≥ 0.38.0&&< 0.38.12 | 0.38.12go get github.com/cometbft/cometbft/light@v0.38.12 |
| 🐹Go | github.com/cometbft/cometbft | ≥ 0.37.0&&< 0.37.11 | 0.37.11go get github.com/cometbft/cometbft@v0.37.11 |
| 🐹Go | github.com/cometbft/cometbft | ≥ 0.38.0&&< 0.38.12 | 0.38.12go get github.com/cometbft/cometbft@v0.38.12 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/cometbft/cometbft/light, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/cometbft/cometbft/light to 0.34.34 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-g5xx-c4hv-9ccc is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-g5xx-c4hv-9ccc can be triaged on real exposure rather than presence alone.
Tailored to GHSA-g5xx-c4hv-9ccc. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-g5xx-c4hv-9ccc in your dependencies?
O3 Security finds GHSA-g5xx-c4hv-9ccc across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.