Improper Certificate Validation vulnerability in the WebSocket streaming client in agentjido reqllm 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/reqllm/streaming/websocketsession/client.ex starts WebSockex without TLS options, and WebSockex defaults to insecure: true, which connects with verify: :verifynone. The option allowlist also drops any caller-supplied cacerts or ssloptions, 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 reqllm: from 1.9.0 before 1.29.0.