PT-2026-40968 · Go · Github.Com/Fleetdm/Fleet/V4
Published
2026-05-14
·
Updated
2026-05-14
·
CVE-2026-24000
CVSS v4.0
6.9
Medium
| Vector | AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N |
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 security@fleetdm.com
Join #fleet in [osquery Slack](https://join.slack.com/t/osquery/shared invite/zt-h29zm0gk-s2DBtGUTW4CFel0f0IjTEw)
Credits
We thank @fuzzztf for responsibly reporting this issue.
Fix
Authentication Bypass by Spoofing
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Weakness Enumeration
Related Identifiers
Affected Products
Github.Com/Fleetdm/Fleet/V4