GHSA-x462-jjpc-q4q4 PraisonAI: Cross-Origin Agent Execution via Hardcoded Wildcard CORS and Missing Authentication on AGUI Endpoint
SummaryThe AGUI endpoint (`POST /agui`) has no authentication and hardcodes `Access-Control-Allow-Origin: *` on all responses. Combined with Starlette/FastAPI's Content-Type-agnostic JSON parsing, any website a victim visits can silently trigger arbitrary agent execution against a locally-running AGUI server and read the full response, including tool execution results and potentially sensitive data from the victim's environment.DetailsThe vulnerability is a combination of three issues in `src/praisonai-agents/praisonaiagents/ui/agui/agui.py`:**1. No authentication (line 124-125):**The endpoint accepts any request. `RunAgentInput` (defined in `types.py:159-165`) has no auth token, API key, or session validation field. No middleware or dependencies are attached to the router (line 111).**2. Hardcoded wildcard CORS (line 131-141):**The `Access-Control-Allow-Origin: *` header is hardcoded in the library code. Library consumers cannot override this without patching the source.**3. CORS preflight bypass via Starlette's Content-Type-agnostic parsing:**
Starlette's `Request.json()` (used internally by FastAPI for Pydantic body models) calls `json.loads(await self.body())` without verifying that `Content-Type` is `application/json`. A browser POST with `Content-Type: text/plain` is classified as a CORS "simple request" per the Fetch specification — no preflight OPTIONS request is sent. Since the JSON body is still parsed successfully, the request executes normally.**Attack flow:**Victim runs an AGUI server locally (the documented usage pattern per the class docstring at lines 42-50)Victim visits an attacker-controlled websiteAttacker's JavaScript sends `POST` to `http://localhost:8000/agui` with `Content-Type: text/plain` containing a JSON body — this is a simple request, no preflightFastAPI parses the JSON body into `RunAgentInput`, the agent executes with full tool capabilitiesThe streaming response includes `Access-Control-Allow-Origin: *`, so the browser permits the attacker's JavaScript to read the responseAttacker exfiltrates the agent's output, including any tool execution resultsPoC**Prerequisites:** A locally running AGUI server (the default setup from documentation):**Exploit (runs on any website the victim visits):****Expected result:** The agent executes the attacker's prompt with whatever tools are configured (file access, code execution, API calls), and the full streamed response is readable by the attacker's JavaScript due to the wildcard CORS header.Impact**Remote code/tool execution**: Any website can trigger agent execution on a victim's local machine with the full permissions of the server process and all configured agent tools**Data exfiltration**: Agent responses (including tool outputs like file contents, command results, API responses) are readable cross-origin due to the wildcard CORS header**No user awareness**: The attack is silent — no browser prompts, no visible indicators. The victim only needs to have the AGUI server running and visit a malicious page**Blast radius**: Impact depends on the agent's configured tools but can include filesystem access, environment variable exposure, network requests from the victim's machine, and arbitrary code execution if code-execution tools are enabledRecommended Fix**1. Remove the hardcoded wildcard CORS headers and make CORS configurable:****2. Remove CORS headers from the StreamingResponse** and let consumers configure CORS via FastAPI's `CORSMiddleware` with specific origins:**3. Add a Content-Type check** as defense-in-depth to prevent simple-request CORS bypass:**4. Add authentication support** (e.g., an API key or bearer token dependency on the router) so that cross-origin requests without valid credentials are rejected.
CVSS v3.1 score: 8.1