GHSA-j8h8-75h3-jg53 — v4
MEDIUMGHSA-j8h8-75h3-jg53 is a medium-severity (CVSS 5.3) CWE-290 vulnerability in github.com/fleetdm/fleet/v4. A fix is available for github.com/fleetdm/fleet/v4 — see the affected versions and patch details below.
Fleet has a rate limiting bypass via untrusted client IP headers
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-j8h8-75h3-jg53 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 379,842 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
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
Impact
Fleet trusted client-supplied IP address headers when determining the source IP for incoming requests. This allowed authenticated and unauthenticated clients to spoof their apparent IP address and bypass per-IP rate limiting controls.
Fleet determines a client’s public IP address using HTTP headers such as:
- X-Forwarded-For
- X-Real-IP
- True-Client-IP
These headers were trusted without validation. An attacker could supply arbitrary values in these headers, causing Fleet to treat each request as originating from a different IP address.
This could allow an attacker to bypass per-IP rate limits and increase the effectiveness of brute-force or password-spraying attempts against authentication endpoints.
This issue does not allow authentication bypass, privilege escalation, data exposure, or remote code execution on its own.
Workarounds
Run Fleet behind a trusted reverse proxy or load balancer that overwrites client IP headers.
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 | 4.80.1go get github.com/fleetdm/fleet/v4@v4.80.1 |
Affected Products
fleetfleetdmDetection & 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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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-j8h8-75h3-jg53 is resolved across your whole dependency graph.
Workarounds
Close the privilege gap rather than the entry point: audit which accounts, roles and service identities can reach the affected operation, drop the component to the least privilege it actually needs, and review file and directory permissions created by earlier installs — a default left in place is what makes this reachable.
Frequently Asked Questions
Is GHSA-j8h8-75h3-jg53 in your dependencies?
Find it across Go, including transitive dependencies.