GHSA-x67p-9m2r-fxqv
GHSA-x67p-9m2r-fxqv is a Improper Input Validation vulnerability in github.com/fleetdm/fleet/v4. O3 Security confirms whether GHSA-x67p-9m2r-fxqv is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Fleet server may terminate unexpectedly when handling certain gRPC requests
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.
Real-World Exposure
github.com/fleetdm/fleet/v4Real-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
Summary
Fleet contained a denial-of-service (DoS) issue in the gRPC Launcher PublishLogs endpoint. In affected versions, certain unexpected input values were not handled gracefully, which could cause the Fleet server process to terminate while processing an authenticated request from an enrolled Launcher host.
Impact
An authenticated attacker with access to any enrolled Launcher node key could cause an immediate and complete denial of service by sending a single gRPC request to the PublishLogs endpoint.
This vulnerability impacts availability only. There is:
- No exposure of sensitive data
- No authentication bypass
- No privilege escalation
- No integrity impact
Workarounds
If upgrading immediately is not possible, the following mitigations can reduce exposure:
- Restrict network access to the Fleet gRPC endpoint where feasible (for example, limiting inbound access to known host IP ranges).
- Deploy Fleet behind infrastructure that terminates or filters gRPC traffic if Launcher log ingestion is not required.
- Monitor for repeated Fleet process crashes or unexpected restarts indicating potential exploitation.
For More Information
If you have any questions or concerns about this advisory, please contact us at:
Email us at [email protected]
Credits
We thank @fuzzztf for responsibly reporting this issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/fleetdm/fleet/v4 | all versions | 4.81.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/fleetdm/fleet/v4. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/fleetdm/fleet/v4 to 4.81.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-x67p-9m2r-fxqv 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 pinpoints whether GHSA-x67p-9m2r-fxqv is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-x67p-9m2r-fxqv. 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-x67p-9m2r-fxqv in your dependencies?
O3 detects GHSA-x67p-9m2r-fxqv across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.