GHSA-mvj3-qrqh-cjvr is a medium-severity (CVSS 5.3) CWE-401 vulnerability in github.com/cometbft/cometbft. 2 public exploit references exist, so weaponization risk is real. A fix is available for github.com/cometbft/cometbft — see the affected versions and patch details below.
CometBFT PeerState JSON serialization deadlock
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-mvj3-qrqh-cjvr.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-mvj3-qrqh-cjvr plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,333 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
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
Impact
An internal modification to the way struct PeerState is serialized to JSON introduced a deadlock when new function MarshallJSON is called. This function can be called from two places:
- Via logs
- Setting the
consensuslogging module to "debug" level (should not happen in production), and - Setting the log output format to JSON
- Setting the
- Via RPC
dump_consensus_state
Case 1 above, which should not be hit in production, will eventually hit the deadlock in most goroutines, effectively halting the node.
In case 2, only the data structures related to the first peer will be deadlocked, together with the thread(s) dealing with the RPC request(s). This means that only one of the channels of communication to the node's peers will be blocked. Eventually the peer will timeout and excluded from the list (typically after 2 minutes). The goroutines involved in the deadlock will not be garbage collected, but they will not interfere with the system after the peer is excluded.
The theoretical worst case for case 2, is a network with only two validator nodes. In this case, each of the nodes only has one PeerState struct. If dump_consensus_state is called in either node (or both), the chain will halt until the peer connections time out, after which the nodes will reconnect (with different PeerState structs) and the chain will progress again. Then, the same process can be repeated.
As the number of nodes in a network increases, and thus, the number of peer struct each node maintains, the possibility of reproducing the perturbation visible with 2 nodes decreases. Only the first PeerState struct will deadlock, and not the others (RPC dump_consensus_state accesses them in a for loop, so the deadlock at the first iteration causes the rest of the iterations of that "for" loop to never be reached).
This regression was introduced in versions v0.34.28 and v0.37.1, and will be fixed in v0.34.29 and v0.37.2.
Patches
The PR containing the fix is here, and the corresponding issue is here
Workarounds
For case 1 (hitting the deadlock via logs)
- either don't set the log output to "json", leave at "plain",
- or don't set the consensus logging module to "debug", leave it at "info" or higher.
For case 2 (hitting the deadlock via RPC dump_consensus_state)
- do not expose
dump_consensus_stateRPC endpoint to the public internet (e.g., via rules in your nginx setup)
References
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/cometbft/cometbft | ≥ 0.34.28&&< 0.34.29 | 0.34.29go get github.com/cometbft/cometbft@v0.34.29 |
| 🐹Go | github.com/cometbft/cometbft | ≥ 0.37.1&&< 0.37.2 | 0.37.2go get github.com/cometbft/cometbft@v0.37.2 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/cometbft/cometbft to 0.34.29 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mvj3-qrqh-cjvr 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-mvj3-qrqh-cjvr can be triaged on real exposure rather than presence alone.
Tailored to GHSA-mvj3-qrqh-cjvr. 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-mvj3-qrqh-cjvr in your dependencies?
O3 Security finds GHSA-mvj3-qrqh-cjvr across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.