GHSA-4JC5-G844-4X33

Vulnerability from github – Published: 2026-07-30 14:46 – Updated: 2026-07-30 14:46
VLAI
Summary
linuxfabrik-lib: fetch() forwards credential headers across a cross-origin redirect
Details

Summary

lib.url.fetch() follows HTTP redirects (follow_redirects=True). httpx strips only Authorization and Cookie when a redirect crosses the origin, so any other caller-supplied credential header (a session token such as Redfish's X-Auth-Token, an API key, ...) was still sent to the redirect target. A malicious or redirect-capable server can therefore answer an authenticated request with a 3xx to an attacker-chosen host and receive the credential (server-side request forgery + token disclosure). The pre-httpx urllib implementation was worse: it forwarded every header, including Authorization, across cross-host redirects.

Impact

Any plugin that authenticates to a host with a non-standard auth header and follows that host's redirects can be coerced into sending the credential, and an authenticated request, to another host the monitoring server can reach. The concrete case is the Redfish checks (X-Auth-Token), but the flaw is in the shared fetch() and affects every consumer.

Patches

Fixed in linuxfabrik-lib 6.0.0 (commit 6573ff9). On a cross-origin redirect (any scheme/host/port change other than a plain same-host HTTP-to-HTTPS upgrade) fetch() now keeps only benign transport headers and drops every other caller-supplied header, so credentials never follow a redirect to a different origin.

Severity
6.0 (Medium)
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "linuxfabrik-lib"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.0.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-67435"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-200",
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-30T14:46:13Z",
    "nvd_published_at": "2026-07-29T20:17:12Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\n`lib.url.fetch()` follows HTTP redirects (`follow_redirects=True`). httpx strips only `Authorization` and `Cookie` when a redirect crosses the origin, so any other caller-supplied credential header (a session token such as Redfish\u0027s `X-Auth-Token`, an API key, ...) was still sent to the redirect target. A malicious or redirect-capable server can therefore answer an authenticated request with a `3xx` to an attacker-chosen host and receive the credential (server-side request forgery + token disclosure). The pre-httpx `urllib` implementation was worse: it forwarded every header, including `Authorization`, across cross-host redirects.\n\n### Impact\nAny plugin that authenticates to a host with a non-standard auth header and follows that host\u0027s redirects can be coerced into sending the credential, and an authenticated request, to another host the monitoring server can reach. The concrete case is the Redfish checks (`X-Auth-Token`), but the flaw is in the shared `fetch()` and affects every consumer.\n\n### Patches\nFixed in linuxfabrik-lib 6.0.0 (commit 6573ff9). On a cross-origin redirect (any scheme/host/port change other than a plain same-host HTTP-to-HTTPS upgrade) `fetch()` now keeps only benign transport headers and drops every other caller-supplied header, so credentials never follow a redirect to a different origin.",
  "id": "GHSA-4jc5-g844-4x33",
  "modified": "2026-07-30T14:46:13Z",
  "published": "2026-07-30T14:46:13Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/Linuxfabrik/monitoring-plugins/security/advisories/GHSA-4jc5-g844-4x33"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-67435"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Linuxfabrik/lib/commit/6573ff9347e541200305d278d2663d2e54e052ff"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Linuxfabrik/lib/releases/tag/v6.0.0"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/Linuxfabrik/monitoring-plugins"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "linuxfabrik-lib: fetch() forwards credential headers across a cross-origin redirect"
}



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