9router: Unauthenticated LLM proxy access via /codex rewrite authorization bypass — GHSA-8GMQ-J984-VP4R

Summary

## Summary 9router exposes an OpenAI/Anthropic-compatible LLM proxy. Remote access to this proxy is intended to be protected by an API-key check in the Next.js middleware. However, 9router also defines a rewrite that maps `/codex/*` to the backend LLM endpoint `/api/v1/responses`. The middleware authorization decision is made on the incoming request path before the rewrite is applied. Because `/codex` is not…

Timeline

Published by source

2026-08-28

Risk context

• Reported severity or threat level: high.
• Reported CVSS score: 8.6 out of 10.
• Reported EPSS value: 0.00611.
• Review exposure for the affected product or family: npm: 9router.

Product

npm: 9router

What to do

General, cautious steps (verify details in the official source):

• Prioritize patching or mitigation immediately (treat as actively risky).
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source
• CVE Record
• NVD

Evidence and provenance

Canonical advisory ID

GHSA-8GMQ-J984-VP4R

Source

GitHub

Vendor

GitHub

Published by source

2026-08-28

Last source activity

2026-08-28

Additional identifiers

CVE-2026-55638

Curated by

hlukh.ch

Related advisories and connections

These advisories are connected by shared CVE, product, vendor, source, or time signals.