GHSA-J8H8-75H3-JG53

Vulnerability from github – Published: 2026-05-14 13:13 – Updated: 2026-05-15 23:44
VLAI?
Summary
Fleet has a rate limiting bypass via untrusted client IP headers
Details

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

Credits

We thank @fuzzztf for responsibly reporting this issue.

Severity ?
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
6.9 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/fleetdm/fleet/v4"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.80.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-24000"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-290"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-14T13:13:39Z",
    "nvd_published_at": "2026-05-14T20:17:01Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nFleet 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.\n\nFleet determines a client\u2019s public IP address using HTTP headers such as:\n- X-Forwarded-For\n- X-Real-IP\n- True-Client-IP\n\nThese 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.\n\nThis could allow an attacker to bypass per-IP rate limits and increase the effectiveness of brute-force or password-spraying attempts against authentication endpoints.\n\nThis issue does not allow authentication bypass, privilege escalation, data exposure, or remote code execution on its own.\n\n### Workarounds\n\nRun Fleet behind a trusted reverse proxy or load balancer that overwrites client IP headers.\n\n### For more information\n\nIf you have any questions or comments about this advisory:\n\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\n\nWe thank @fuzzztf for responsibly reporting this issue.",
  "id": "GHSA-j8h8-75h3-jg53",
  "modified": "2026-05-15T23:44:40Z",
  "published": "2026-05-14T13:13:39Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/fleetdm/fleet/security/advisories/GHSA-j8h8-75h3-jg53"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-24000"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/fleetdm/fleet"
    },
    {
      "type": "WEB",
      "url": "https://github.com/fleetdm/fleet/releases/tag/fleet-v4.80.1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Fleet has a rate limiting bypass via untrusted client IP headers"
}


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Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.