# 9Router has an Authentication Bypass in Public LLM API via Spoofable X-9r-Real-Ip Header

Advisory record · `GHSA-5mj8-gf6m-fhw8`

- **Identifiers:** `GHSA-5mj8-gf6m-fhw8` · `CVE-2026-56681`
- **State:** Confirmed
- **Severity:** CVSS 7.3 High
- **Critical:** No
- **Weakness (CWE):** [CWE-807](https://cwe.mitre.org/data/definitions/807.html)
- **Tags:** [CWE-807](https://agentprime.io/advisories/tag/cwe-807.md)
- **Published:** 22 Sept 2026
- **Updated:** 22 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 22 Sept 2026, 16:34 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `9router` (npm): affected `<0.5.8`; fixed in `0.5.8`

## 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

- 7.3 High, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.011, the 66th percentile, on 7 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

This record came from the full history of the GitHub Advisory Database, published 22 Sept 2026. New records show when each source confirmed them.

## Sources

- [GitHub Advisory Database: GHSA-5mj8-gf6m-fhw8](https://github.com/advisories/GHSA-5mj8-gf6m-fhw8)
- [OSV: GHSA-5mj8-gf6m-fhw8](https://osv.dev/vulnerability/GHSA-5mj8-gf6m-fhw8)
- <https://github.com/decolua/9router/security/advisories/GHSA-5mj8-gf6m-fhw8>
- <https://github.com/decolua/9router/commit/efd20be8d81ef2e256a7037f3aa78e6b567b5fd3>
- <https://github.com/decolua/9router>
- <https://github.com/decolua/9router/releases/tag/v0.5.6>

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-5mj8-gf6m-fhw8>, 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-5mj8-gf6m-fhw8/>. Everything for agents: <https://agentprime.io/llms.txt>.