# CVE-2026-55638: decolua 9router auth bypass via /codex rewrite

Source: https://junglewise.ai/threats/cve-2026-55638-decolua-9router-auth-bypass-via-codex-rewrite  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-10. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-55638 · Severity: high · CVSS 8.6 · Published 2026-07-10

9router is a proxy service that provides an OpenAI/Anthropic-compatible LLM (large language model) interface, designed to be protected by API-key authentication. However, a flaw in how the application handles URL rewrites allows unauthenticated attackers to bypass the API-key check by sending requests to the `/codex/*` endpoint instead of the protected `/api/v1/*` endpoint. This allows attackers to use the service operator's credentials to make LLM API calls, consume their provider credits, and incur unexpected billing charges.

Technologies: [9router (npm)](https://junglewise.ai/threats/technologies/9router). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2026-55638 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-55638 being exploited in the wild.

**How severe is CVE-2026-55638?** High severity, with a CVSS score of 8.6, published 10 July 2026.

**Which products and versions are affected?** 9router (npm) < 0.5.2, SEMVER:introduced=0,fixed=0.5.2.

**Is there a fix for CVE-2026-55638?** Yes. 9router (npm): upgrade to 0.5.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-55638 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-55638?** Check whether you run 9router (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- 9router (npm): upgrade to 0.5.2 or later

  ```sh
  npm install 9router@0.5.2
  ```


## Technical details

This is an authorization bypass vulnerability in 9router's Next.js middleware logic. The vulnerability stems from a timing mismatch in the request authorization flow: the middleware in `src/dashboardGuard.js` evaluates whether a request requires an API key based on the original request path before Next.js URL rewrites are applied. The protected prefix list includes `/v1`, `/v1beta`, `/api/v1`, and `/api/v1beta`, but excludes `/codex`. The `next.config.mjs` configuration contains a rewrite rule mapping `/codex/:path*` to `/api/v1/responses`. When an attacker sends a POST request to `/codex/x`, the middleware allows it to pass (because `/codex` is not protected), and the request is then rewritten to `/api/v1/responses` where it is processed by the chat handler using the operator's stored LLM provider API keys. The vulnerability is network-accessible with no authentication required and no user interaction needed. A patch is available in version 0.5.2.

## Affected products

- decolua 9router < 0.5.2

## Identifiers

- CVE-2026-55638
- GHSA-8gmq-j984-vp4r

## Timeline

- 2026-07-07: disclosed
- 2026-07-10: patched: patch released in v0.5.2
- 2026-08-28: advisory

## References

- [https://api.github.com/users/dinhvaren](https://api.github.com/users/dinhvaren)
- [https://github.com/dinhvaren](https://github.com/dinhvaren)
- [https://api.github.com/users/dinhvaren/gists%7B/gist_id%7D](https://api.github.com/users/dinhvaren/gists%7B/gist_id%7D)
- [https://api.github.com/users/dinhvaren/repos](https://api.github.com/users/dinhvaren/repos)
- [https://avatars.githubusercontent.com/u/149681061?v=4](https://avatars.githubusercontent.com/u/149681061?v=4)
- [https://api.github.com/users/dinhvaren/events%7B/privacy%7D](https://api.github.com/users/dinhvaren/events%7B/privacy%7D)

## Related threats

- [9Router has a Login Brute-Force Lockout Bypass via Spoofable X-9r-Real-Ip Header](https://junglewise.ai/threats/cve-2026-56682-9router-login-brute-force-lockout-bypass-via-spoofable-header)
- [9Router has an Authentication Bypass in Public LLM API via Spoofable X-9r-Real-Ip Header](https://junglewise.ai/threats/cve-2026-56681-9router-authentication-bypass-in-public-llm-api-via-spoofable-x)
- [9Router unauthenticated server-side request forgery in OIDC test endpoint](https://junglewise.ai/threats/cve-2026-56677-9router-unauthenticated-server-side-request-forgery-in-oidc-test)
- [decolua 9Router mass assignment in /api/settings](https://junglewise.ai/threats/cve-2026-56679-decolua-9router-mass-assignment-in-api-settings)
- [decolua 9router SSRF and credential forwarding in Kiro API validation](https://junglewise.ai/threats/cve-2026-56678-decolua-9router-ssrf-and-credential-forwarding-in-kiro-api)