CVE-2026-55500

9router 0.4.59 contains a chain of vulnerabilities: a hardcoded default password (123456), a bypass of the LOCAL_ONLY network gate via a spoofed Host header, and unvalidated arguments passed to child_process.spawn() when registering MCP plugins. A remote, unauthenticated attacker can log in with the default credential, spoof the Host header to reach local-only routes, and register a malicious MCP plugin to achieve arbitrary code execution on the host operating system.

In 9Router versions 0.2.21 through 0.4.44, a hardcoded fallback JWT secret '9router-default-secret-change-me' was used, allowing attackers to forge an auth_token cookie when JWT_SECRET is unset. The issue is fixed in version 0.4.44.

In 9Router versions 0.4.30 through 0.4.37, the middleware in src/proxy.js did not protect /api/cli-tools/* and /api/mcp/*, allowing unauthenticated plugin registration and command execution via the MCP bridge. This vulnerability is fixed in version 0.4.37.

9Router through version 0.4.41 contains an unauthenticated information disclosure vulnerability that allows remote attackers to retrieve plaintext API keys for all connected AI provider accounts by sending a single unauthenticated request to the /api/usage/stats endpoint. Attackers can exploit the missing authentication middleware on the Next.js API route to obtain full API key strings alongside token counts, cost breakdowns, and request metadata.

9Router through version 0.4.41 contains an unauthenticated access vulnerability allowing remote attackers to interact with provider management API endpoints without credentials due to missing authentication middleware in Next.js API routes under src/app/api/providers/*. Attackers can enumerate, create, modify, or delete provider connections.

9Router before version 0.4.44 contains an OS command injection vulnerability in the unauthenticated POST /api/tunnel/tailscale-install endpoint. The sudoPassword field from the request body is passed to the stdin of a 'sudo -S sh' process, allowing a remote unauthenticated attacker to execute arbitrary OS commands.

9router versions 0.4.1 through 0.5.99 contain a configuration injection vulnerability in the POST /api/cli-tools/hermes-settings endpoint that allows authenticated dashboard users to inject arbitrary keys into the Hermes Agent config.yaml file. Attackers can submit a baseUrl containing double quotes and newlines to add hooks_auto_accept and a hooks.post_llm_call shell command, which Hermes Agent executes without approval after an LLM call.

In 9Router prior to 0.5.6, deployments that allow requests to reach Next.js without the sanitizing custom-server.js wrapper use the client-supplied X-9r-Real-Ip value as the bucket key in getClientIp, checkLock, and recordFail in src/lib/auth/loginLimiter.js for POST /api/auth/login. A remote unauthenticated attacker can rotate the header on every password guess so each request uses a new failed-attempt bucket and the five-attempt progressive lockout never returns HTTP 429.

9Router is an AI router & token saver. Prior to 0.5.6, 9Router deployments that allow requests to reach Next.js without the sanitizing custom-server.js wrapper trust the client-supplied X-9r-Real-Ip header in src/dashboardGuard.js when isLocalRequest decides whether canAccessPublicLlmApi may skip API-key validation for /api/v1/* routes. A remote unauthenticated attacker can set X-9r-Real-Ip to 127.0.0.1 and be classified as a local client, including on the verified GET /api/v1/models route. This issue is fixed in version 0.5.6.

An SSRF vulnerability in the POST /api/provider-nodes/validate route in 9router allows an attacker to make server-side requests to internal addresses, including loopback and link-local, due to flaws in the assertPublicUrl guard. Additionally, internal responses may be disclosed, and the API key is forwarded to internal destinations.