GHSA-99hj-44vg-hfcp
Fleet's unbounded request body read allows remote Denial of Service
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.
Blast Radius
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 multiple unauthenticated HTTP endpoints that read request bodies without enforcing a size limit. An unauthenticated attacker could exploit this behavior by sending large or repeated HTTP payloads, causing excessive memory allocation and resulting in a denial-of-service (DoS) condition.
Impact
An unauthenticated attacker could cause the Fleet server process to exhaust available memory and restart by sending oversized or repeated HTTP requests to affected endpoints.
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:
- Apply request body size limits at a reverse proxy or load balancer (e.g., NGINX, Envoy).
- Restrict network access to endpoints to known IP ranges where feasible.
- Monitor memory usage and restart frequency for abnormal patterns.
For More Information
If there are any questions or concerns about this advisory, please contact us at:
Email Fleet at [email protected]
Credits
Fleet thanks @fuzzztf for responsibly reporting this issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/fleetdm/fleet/v4 | all versions | 4.43.5-0.20260113202849-bbc1aef2987d |
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 4.43.5-0.20260113202849-bbc1aef2987d or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-99hj-44vg-hfcp 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-99hj-44vg-hfcp 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-99hj-44vg-hfcp. 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-99hj-44vg-hfcp in your dependencies?
O3 detects GHSA-99hj-44vg-hfcp across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.