GHSA-mxmp-wr3w-rvqx
GHSA-mxmp-wr3w-rvqx is a CWE-290 vulnerability in github.com/fleetdm/fleet/v4. O3 Security confirms whether GHSA-mxmp-wr3w-rvqx is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Fleet: IP spoofing allows bypassing API rate limiting
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- 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-mxmp-wr3w-rvqx.
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
A vulnerability in Fleet's IP extraction logic allows unauthenticated attackers to bypass API rate limiting by spoofing client IP headers. This may allow brute-force login attempts or other abuse against Fleet instances exposed to the public internet.
Impact
Fleet extracted client IP addresses from request headers (True-Client-IP, X-Real-IP, X-Forwarded-For) without validating that those headers originate from a trusted proxy. The extracted IP is used as the key for rate limiting and IP ban decisions.
As a result, an attacker could rotate the value of these headers on each request, causing Fleet to treat each attempt as coming from a different client. This effectively bypasses per-IP rate limits on sensitive endpoints such as the login API, enabling unrestricted brute-force or credential stuffing attacks.
This issue primarily affects Fleet instances that are directly exposed to the internet without a reverse proxy that overwrites forwarded-IP headers. Instances behind a properly configured proxy or WAF are less affected.
Workarounds
If an immediate upgrade is not possible, administrators should ensure Fleet is deployed behind a reverse proxy (e.g., nginx, Cloudflare, AWS ALB) that overwrites X-Forwarded-For with the true client IP, and apply rate limiting at the proxy or WAF layer.
For more information
If you have any questions or comments about this advisory: Email us at [email protected] Join #fleet in osquery Slack
Credits
We thank @fuzzztf for responsibly reporting this issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/fleetdm/fleet/v4 | all versions | 4.80.1 |
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 4.80.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mxmp-wr3w-rvqx 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-mxmp-wr3w-rvqx 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-mxmp-wr3w-rvqx. 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-mxmp-wr3w-rvqx in your dependencies?
O3 detects GHSA-mxmp-wr3w-rvqx across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.