GHSA-mxmp-wr3w-rvqx
Suggest an improvement- Source
- https://github.com/advisories/GHSA-mxmp-wr3w-rvqx
- Import Source
- https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-mxmp-wr3w-rvqx/GHSA-mxmp-wr3w-rvqx.json
- JSON Data
- https://api.osv.dev/v1/vulns/GHSA-mxmp-wr3w-rvqx
- Aliases
- Published
- 2026-05-14T13:18:33Z
- Modified
- 2026-06-25T23:11:45Z
- Severity
-
- 6.9 (Medium) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N CVSS Calculator
- Summary
- Fleet: IP spoofing allows bypassing API rate limiting
- Details
-
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-Forwith 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 security@fleetdm.com Join #fleet in osquery Slack
Credits
We thank @fuzzztf for responsibly reporting this issue.
- Database specific
{ "cwe_ids": [ "CWE-290" ], "github_reviewed": true, "github_reviewed_at": "2026-05-14T13:18:33Z", "nvd_published_at": "2026-05-14T20:17:09Z", "severity": "MODERATE" }- References
Affected packages
Go / github.com/fleetdm/fleet/v4
Package
- Name
- github.com/fleetdm/fleet/v4
- View open source insights on deps.dev
- Purl
- pkg:golang/github.com/fleetdm/fleet/v4