WebSocket sessions do not verify TLS certificates, exposing API keys and OAuth tokens to on-path attackers

Overview

Improper Certificate Validation vulnerability in the WebSocket streaming client in agentjido req_llm allows an on-path attacker to read and modify OpenAI WebSocket sessions, including the authorization bearer token, via a TLS certificate the client does not trust. ReqLLM.Streaming.WebSocketSession.Client.start/3 in lib/req_llm/streaming/web_socket_session/client.ex starts WebSockex without TLS options, and WebSockex defaults to insecure: true, which connects with verify: :verify_none. The option allowlist also drops any caller-supplied cacerts or ssl_options, so an application cannot turn verification on.

The OpenAI Responses, Realtime, and Codex WebSocket paths reach this client and send the API key or OAuth access token in the authorization header. HTTP streaming through Finch and the HTTP/2 duplex session through Mint verify certificates and are not affected.

This issue affects req_llm: from 1.9.0 before 1.29.0.

Affected

• req_llm >= 1.9.0 < 1.29.0
• agentjido/req_llm >= a389d718640ceb2d541a8f540ab954cbf5ef8313 < c7264fc0217fbacfb5562234ff790b8e4462de76

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

Workarounds

Leave the openai_stream_transport provider option at its default :sse for the OpenAI and OpenAI Codex providers, and do not call ReqLLM.Providers.OpenAI.WebSocket.start_responses_session/2 directly. Responses streaming then runs over HTTP through Finch, which verifies certificates. ReqLLM.OpenAI.Realtime.connect/2 has no HTTP alternative, so do not use it on an affected version.