CVE-2026-67435: linuxfabrik-lib Fetch() Forwards Credential Headers Across Vulnerability

MODERATE
Advisory Identifier: GHSA-4jc5-g844-4x33
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CWE-918 CWE-200
Published
Advisory Summary

CVE-2026-67435 is a MODERATE fetch() forwards credential headers across vulnerability (CWE-918: Server-Side Request Forgery (SSRF)) affecting linuxfabrik-lib libraries in the PyPI ecosystem. The issue involves fetch() forwards credential headers across a cross-origin redirect. Remediation is available by upgrading affected packages to version 6.0.0.

CVE-2026-67435 at a Glance

CVE Identifier CVE-2026-67435
GHSA Identifier GHSA-4jc5-g844-4x33
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-918: Server-Side Request Forgery (SSRF)
Affected Product linuxfabrik-lib
Package Ecosystem PyPI
Published Date
Last Updated

How to Fix CVE-2026-67435

To remediate this vulnerability, upgrade all affected linuxfabrik-lib dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

linuxfabrik-lib fixed: 6.0.0 
pip install linuxfabrik-lib>=6.0.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show linuxfabrik-lib

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-67435, inspect your installed packages using pip:

pip show linuxfabrik-lib

Analyze the terminal output to locate any version of linuxfabrik-lib in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 6.0.0), your application is affected.

Note: The pip show linuxfabrik-lib command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-918: Server-Side Request Forgery (SSRF), where the web server receives a url or similar request from an upstream component and retrieves the contents of this url, but it does not sufficiently ensure that the request is being sent to the expected destination. In linuxfabrik-lib, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### 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.

CVE-2026-67435 Affected linuxfabrik-lib Versions

1 component(s)
Fixed Versions:
6.0.0
Product / Package Ecosystem Affected Versions Fixed Version
linuxfabrik-lib
pypi/linuxfabrik-lib
PyPI
< 6.0.0
6.0.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/Linuxfabrik/monitoring-plugins/security/advisories/GHSA-4jc5-g844-4x33
NVD — CVE-2026-67435 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-67435
Security Fix Commit FIX COMMIT
https://github.com/Linuxfabrik/lib/commit/6573ff9347e541200305d278d2663d2e54e052ff
linuxfabrik-lib Release RELEASE
https://github.com/Linuxfabrik/lib/releases/tag/v6.0.0
linuxfabrik-lib Source Repository REPOSITORY
https://github.com/Linuxfabrik/monitoring-plugins

Frequently Asked Questions

What is CVE-2026-67435?
CVE-2026-67435 is a security vulnerability in linuxfabrik-lib involving fetch() forwards credential headers across a cross-origin redirect under CWE-918: Server-Side Request Forgery (SSRF).
Which linuxfabrik-lib versions are affected?
Affected versions include releases prior to 6.0.0 across affected packages: linuxfabrik-lib.
What version fixes CVE-2026-67435?
Upgrading to 6.0.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is linuxfabrik-lib affected?
Yes, linuxfabrik-lib is affected in releases prior to 6.0.0. Upgrade your dependency to 6.0.0 or later.
What CWE is associated with CVE-2026-67435?
CVE-2026-67435 is classified under CWE-918: Server-Side Request Forgery (SSRF) (The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.).
How can I check PyPI dependencies for CVE-2026-67435?
Run the dependency tree command: 'pip show linuxfabrik-lib'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-4jc5-g844-4x33",
  "modified" : "2026-07-30T14:46:13Z",
  "published" : "2026-07-30T14:46:13Z",
  "aliases" : [ "CVE-2026-67435" ],
  "summary" : "linuxfabrik-lib: fetch() forwards credential headers across a cross-origin redirect",
  "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'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.\n\n### Impact\nAny 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.\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.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "linuxfabrik-lib"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "6.0.0"
      } ]
    } ]
  } ],
  "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"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-200", "CWE-918" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-30T14:46:13Z",
    "nvd_published_at" : "2026-07-29T20:17:12Z"
  }
}