Fleet has a rate limiting bypass via untrusted client IP headers
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:
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.
Run Fleet behind a trusted reverse proxy or load balancer that overwrites client IP headers.
If you have any questions or comments about this advisory:
Email us at [security@fleetdm.com](mailto:[email protected])
Join #fleet in [osquery Slack](https://join.slack.com/t/osquery/shared_invite/zt-h29zm0gk-s2DBtGUTW4CFel0f0IjTEw)
We thank @fuzzztf for responsibly reporting this issue.
This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity low, availability none.
The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
CVE-2026-24000 is classified as CWE-290: Authentication Bypass by Spoofing. Identity is inferred from something an attacker can forge, such as a header or address.
CVE-2026-24000 is recorded against 2 packages.
Published on 14 May 2026 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.
fleet has other advisories on record. If you are patching this one, these are worth checking on the same host:
These advisories are the same class of weakness (CWE-290: Authentication Bypass by Spoofing) in other software:
Details
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Affected Packages
| Software | From version | Fixed in |
|---|---|---|
| fleet | — | 4.80.1 |
| github.com/fleetdm/fleet/v4 | — | — |
References
Similar Threats
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