{"id":"GHSA-mxmp-wr3w-rvqx","revision":"74b6ae21e4ba4462a7af9b9d2932d962","records":[{"revision":"74b6ae21e4ba4462a7af9b9d2932d962","observedAt":"2026-10-24T13:19:41.952+00:00","statement":{"source":"osv","id":"GHSA-mxmp-wr3w-rvqx","aliases":["CVE-2026-46356","GO-2026-5520"],"title":"Fleet: IP spoofing allows bypassing API rate limiting","description":"### Summary\nA 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.\n\n### Impact\nFleet 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.\n\nAs 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.\n\nThis 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.\n\n### Workarounds\nIf 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.\n\n### For more information\nIf you have any questions or comments about this advisory:\nEmail us at [security@fleetdm.com](mailto:security@fleetdm.com)\nJoin #fleet in [osquery Slack](https://join.slack.com/t/osquery/shared_invite/zt-h29zm0gk-s2DBtGUTW4CFel0f0IjTEw)\n\n### Credits\nWe thank @fuzzztf for responsibly reporting this issue.","state":0,"publishedAt":"2026-05-14T13:18:33+00:00","modifiedAt":"2026-06-25T23:11:45.2941186+00:00","affected":[{"ecosystem":"Go","name":"github.com/fleetdm/fleet/v4","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"4.80.1"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V4","vector":"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","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"MODERATE"}],"references":["https://github.com/fleetdm/fleet/security/advisories/GHSA-mxmp-wr3w-rvqx","https://nvd.nist.gov/vuln/detail/CVE-2026-46356","https://github.com/fleetdm/fleet","https://github.com/fleetdm/fleet/releases/tag/fleet-v4.80.1"],"sourceUrl":"https://github.com/advisories/GHSA-mxmp-wr3w-rvqx","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-mxmp-wr3w-rvqx","identifiers":["GHSA-mxmp-wr3w-rvqx","CVE-2026-46356","GO-2026-5520"]},"retained":false,"historicalAffected":[]}],"coverage":[]}