IBM Langflow OSS unauthenticated RCE via auto_login token minting and validate/code exec() chain

#!/usr/bin/env bash
# check_cve_2026_9198.sh — CVE-2026-9198 Langflow auto_login auth bypass detector
# Tests whether /api/v1/auto_login mints a SUPERUSER token without credentials.
# Exit codes: 0 = VULNERABLE, 1 = PATCHED, 2 = UNKNOWN

set -euo pipefail

if [ $# -lt 1 ]; then
  echo "Usage: $0 <LANGFLOW_BASE_URL>"
  echo "Example: $0 https://langflow.example.com:7860"
  exit 2
fi

BASE_URL="${1%/}"
ENDPOINT="${BASE_URL}/api/v1/auto_login"

echo "[*] Testing CVE-2026-9198 against: ${BASE_URL}"
echo "[*] Endpoint: ${ENDPOINT}"
echo ""

# Step 1: Attempt unauthenticated auto_login
HTTP_RESPONSE=$(curl -sk -w "\n%{http_code}" -X POST "${ENDPOINT}" \
  -H "Content-Type: application/json" \
  -d '{}' 2>/dev/null) || {
  echo "[!] UNKNOWN — Could not reach ${ENDPOINT}"
  echo "    Verify the URL and network connectivity."
  exit 2
}

HTTP_BODY=$(echo "$HTTP_RESPONSE" | sed '$d')
HTTP_CODE=$(echo "$HTTP_RESPONSE" | tail -1)

echo "[*] HTTP status code: ${HTTP_CODE}"

if [ "$HTTP_CODE" -eq 200 ]; then
  # Check if response contains an access token
  if echo "$HTTP_BODY" | grep -qi '"access_token"'; then
    TOKEN=$(echo "$HTTP_BODY" | python3 -c "import sys,json; print(json.load(sys.stdin).get('access_token',''))" 2>/dev/null || echo "")
    if [ -n "$TOKEN" ]; then
      echo ""
      echo "[!] VULNERABLE — CVE-2026-9198"
      echo "    auto_login returned a token without authentication."
      echo "    Token prefix: ${TOKEN:0:20}..."
      echo ""
      echo "    LANGFLOW_AUTO_LOGIN is likely set to true (the insecure default)."
      echo "    Immediate action: set LANGFLOW_AUTO_LOGIN=false and upgrade to 1.10.2+."
      exit 0
    fi
  fi
  echo ""
  echo "[?] UNKNOWN — Got HTTP 200 but no access_token in response."
  echo "    Manual review recommended."
  exit 2
elif [ "$HTTP_CODE" -eq 403 ] || [ "$HTTP_CODE" -eq 401 ]; then
  echo ""
  echo "[+] PATCHED — auto_login returned ${HTTP_CODE} (authentication required)."
  echo "    LANGFLOW_AUTO_LOGIN appears to be disabled or the endpoint is secured."
  exit 1
elif [ "$HTTP_CODE" -eq 404 ]; then
  echo ""
  echo "[+] PATCHED — auto_login endpoint not found (404)."
  echo "    Endpoint may have been removed in a newer version."
  exit 1
else
  echo ""
  echo "[?] UNKNOWN — Unexpected HTTP status ${HTTP_CODE}."
  echo "    Response body (first 500 chars):"
  echo "$HTTP_BODY" | head -c 500
  exit 2
fi