# linuxfabrik-lib: fetch() forwards credential headers across a cross-origin redirect

Advisory record · `GHSA-4jc5-g844-4x33`

- **Identifiers:** `GHSA-4jc5-g844-4x33` · `CVE-2026-67435` · `PYSEC-2026-3578`
- **State:** Confirmed
- **Severity:** CVSS 6.0 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-200](https://cwe.mitre.org/data/definitions/200.html) · [CWE-918](https://cwe.mitre.org/data/definitions/918.html)
- **Tags:** [Information disclosure](https://agentprime.io/advisories/tag/info-disclosure.md) · [Server-side request forgery (SSRF)](https://agentprime.io/advisories/tag/ssrf.md)
- **Published:** 30 Jul 2026
- **Updated:** 4 Aug 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 30 Jul 2026, 14:46 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `linuxfabrik-lib` (PyPI): affected `<6.0.0`; fixed in `6.0.0`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> Linuxfabrik-lib versions before 6.0.0 are vulnerable. When fetch() follows a redirect to a different origin, it forwards caller-supplied credential headers other than Authorization and Cookie, such as X-Auth-Token or API keys, to the redirect target. An attacker controlling or able to redirect a server the client authenticates to could capture those credentials and cause authenticated requests to be sent to another host the monitoring server can reach. Upgrade to linuxfabrik-lib 6.0.0, which drops all non-transport headers on cross-origin redirects.

Written 5 Nov 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 6.0 Medium, CVSS 4.0: `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`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0050, the 43rd percentile, on 12 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:40 UTC: First seen by agentprime
- 31 Oct 2026, 14:40 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-4jc5-g844-4x33)

## Sources

- [GitHub Advisory Database: GHSA-4jc5-g844-4x33](https://github.com/advisories/GHSA-4jc5-g844-4x33)
- [OSV: GHSA-4jc5-g844-4x33](https://osv.dev/vulnerability/GHSA-4jc5-g844-4x33)
- <https://github.com/Linuxfabrik/monitoring-plugins/security/advisories/GHSA-4jc5-g844-4x33>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-67435>
- <https://github.com/Linuxfabrik/lib/commit/6573ff9347e541200305d278d2663d2e54e052ff>
- <https://github.com/Linuxfabrik/lib/releases/tag/v6.0.0>
- <https://github.com/Linuxfabrik/monitoring-plugins>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-4jc5-g844-4x33>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-4jc5-g844-4x33/>. Everything for agents: <https://agentprime.io/llms.txt>.