GHSA-j8cv-x86q-rj85 Pipecat: Telephony WebSocket `/ws` Unauthenticated Call-Control Abuse via Attacker-Supplied Call SID
Development Runner Telephony WebSocket `/ws` Unauthenticated Call-Control Abuse via Attacker-Supplied Call SIDSummaryThe pipecat development runner registers a `/ws` WebSocket endpoint for telephony testing that accepts connections without any authentication. An unauthenticated remote attacker who can reach an exposed runner endpoint can connect to this endpoint, send a crafted Twilio handshake message containing an attacker-supplied `callSid`, and cause the server to issue an authenticated Twilio REST API hang-up request against that call SID using the server operator's own credentials. This may allow the attacker to forcibly terminate an active call on the victim's Twilio account if the attacker knows or obtains a valid call SID for that account. Equivalent unauthenticated call-control sinks exist for Telnyx and Plivo. Maintainers are evaluating the final CVSS 3.1 score.DetailsThe pipecat development runner registers a WebSocket route at `/ws` (`src/pipecat/runner/run.py:1116`). When a client connects, the server immediately accepts the connection without performing any authentication or signature verification (`run.py:1119`):After acceptance, the server reads the Twilio WebSocket stream-start handshake and extracts the `callSid` field verbatim from the attacker-controlled JSON payload (`src/pipecat/runner/utils.py:223`):The tainted `call_id` is then passed directly into `TwilioFrameSerializer` alongside the server's own Twilio account credentials, which are read from environment variables (`src/pipecat/runner/utils.py:513-517`):`TwilioFrameSerializer` has `auto_hang_up` defaulting to `True` (`src/pipecat/serializers/twilio.py:56`). When the pipeline terminates and serializes an `EndFrame` or `CancelFrame`, `_hang_up_call()` is triggered (`twilio.py:141-147`). This method constructs a Twilio REST API URL containing the attacker-supplied `call_sid` and POSTs to it using the server's own credentials (`twilio.py:196`, `twilio.py:206`):The same unauthenticated call-control pattern exists for Telnyx (`src/pipecat/serializers/telnyx.py:188`, `:195`) and Plivo (`src/pipecat/serializers/plivo.py:180`, `:187`).Although the runner defaults to `localhost` and is documented as a development runner, its telephony mode is commonly used with a public proxy hostname so that telephony providers can connect inbound calls. If the development runner is exposed to untrusted networks while configured with Twilio, Telnyx, or Plivo credentials, this becomes a realistic network-reachable attack surface.PoC**Prerequisites**Docker (for building the isolated PoC image)A clone of the pipecat repository at commit `b982b45a7ae1e5ee99e4390ad5a116cdd9b4a8e2` placed at `<context_root>/repo/`The files `vuln-001/Dockerfile` and `vuln-001/poc.py` present under `<context_root>/`**Step 1 — Build the Docker image**The Dockerfile installs pipecat from the local repository clone, generates a self-signed TLS CA and server certificate for `api.twilio.com`, and registers that CA in the system trust store so that pipecat's `aiohttp`-based HTTP client accepts the mock server certificate.**Step 2 — Run the PoC**The `--add-host` flag redirects DNS resolution for `api.twilio.com` to the loopback interface so all outgoing Twilio REST API calls hit the mock server instead of Twilio's real infrastructure.**What the PoC does**Starts a local TLS-enabled HTTP server on `127.0.0.1:443` that impersonates `api.twilio.com` and records every incoming POST request.Simulates the attacker-controlled WebSocket handshake message with an injected `callSid`:Runs the exact pipecat code path: parses `callSid` from attacker input (`utils.py:223`), constructs `TwilioFrameSerializer` with server credentials (`utils.py:513-517`), and calls `serialize(EndFrame())` which triggers `_hang_up_call()` (`twilio.py:141-147`, `:196`, `:206`).Verifies that the mock server received a POST whose URL contains the attacker-injected call SID.**Expected output (passing)****Observed intercepted request (Phase 2 dynamic reproduction)**Decoding the `Authorization` header confirms `ACFAKE000000000000000000000000001:fake_auth_token_poc_only` — the server's own credentials were used against the attacker-specified call SID.ImpactThis is a Missing Authorization vulnerability (CWE-862) in the development runner's telephony WebSocket handling. An unauthenticated network actor who can reach an exposed `/ws` WebSocket endpoint of a pipecat development runner configured with Twilio, Telnyx, or Plivo credentials may be able to:**Forcibly terminate active calls whose valid call-control identifiers are known or obtained** on the server operator's Twilio, Telnyx, or Plivo account by injecting the victim call identifier into the WebSocket handshake and then triggering pipeline termination.**Cause denial of service** against affected calls by repeatedly terminating calls for which the attacker has valid call-control identifiers.**Abuse the operator's telephony provider credentials** to perform call-control actions that the attacker does not have direct access to, effectively escalating privilege over the operator's telephony account.Impacted parties include operators who expose the pipecat development runner's telephony `/ws` endpoint on a publicly reachable host with Twilio, Telnyx, or Plivo credentials configured, and their customers whose active calls can be disrupted if a valid call-control identifier is known or obtained by an attacker.Reproduction artifacts`Dockerfile``poc.py`ResolutionThis issue was addressed in pipecat-ai `v1.4.0` by adding optional HMAC token authentication for development-runner WebSocket endpoints.Operators who expose the development runner’s WebSocket endpoints to anything other than localhost should upgrade to `v1.4.0` or later and enable WebSocket token authentication:or:When enabled, clients must first call `POST /start` to obtain a short-lived, one-time-use signed token before connecting to `/ws` or `/ws-client`. Tokens may be supplied via
`Authorization: Bearer <token>`, `?token=<token>`, or as a path segment such as `/ws/<token>`, which is intended for telephony providers that cannot set custom headers. Invalid,
expired, or replayed tokens are rejected with WebSocket close code `4003`.The fix was merged in https://github.com/pipecat-ai/pipecat/pull/4660.
CVSS v3.1 score: 7.5