GHSA-vg9h-jx4v-cwx2: Dfir unfurl Unfurl's Debug Mode Cannot Be Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-vg9h-jx4v-cwx2",
  "modified" : "2026-01-29T15:32:33Z",
  "published" : "2026-01-29T15:32:33Z",
  "aliases" : [ ],
  "summary" : "Unfurl's debug mode cannot be disabled due to string config parsing (Werkzeug debugger exposure)",
  "details" : "### Summary\nThe Unfurl web app enables Flask debug mode even when configuration sets `debug = False`. The config value is read as a string and passed directly to `app.run(debug=...)`, so any non-empty string evaluates truthy. This leaves the Werkzeug debugger active by default.\n\n### Details\n- `unfurl/app.py:web_app()` reads `debug` via `config['UNFURL_APP'].get('debug')`, which returns a string.\n- `UnfurlApp.__init__` passes that string directly to `app.run(debug=unfurl_debug, ...)`.\n- If `unfurl.ini` omits `debug`, the default argument is the string `\"True\"`.\n- As a result, debug mode is effectively always on and cannot be reliably disabled via config.\n\n### PoC\n1. Create a local `unfurl.ini` with `debug = False` under `[UNFURL_APP]`.\n2. Run the server using `unfurl_app` (or `python -c 'from unfurl.app import web_app; web_app()'`).\n3. Observe server logs showing `Debug mode: on` / `Debugger is active!`.\n4. The included PoC script `security_poc/poc_debug_mode.py --spawn` automates this check.\n\n### PoC Script (inline)\n```python\n#!/usr/bin/env python3\n\"\"\"\nUnfurl Debug Mode PoC (Corrected)\n================================\n\nThis PoC demonstrates that Unfurl's Flask debug mode is effectively\n**always enabled by default** due to string parsing of the `debug`\nconfig value. Even `debug = False` in `unfurl.ini` evaluates truthy\nwhen passed to `app.run(debug=...)`.\n\nTwo modes:\n1) --spawn (default): launch a local Unfurl server with debug=False\n   in a temp config and inspect logs for \"Debug mode: on\".\n2) --target: attempt a remote indicator check (best-effort; may be silent\n   if no exception is triggered).\n\"\"\"\n\nimport argparse\nimport os\nimport subprocess\nimport sys\nimport tempfile\nimport textwrap\nimport time\n\n\ndef run_spawn_check() -> None:\n    repo_root = os.path.abspath(os.path.join(os.path.dirname(__file__), '..'))\n\n    ini_contents = textwrap.dedent(\"\"\"\n    [UNFURL_APP]\n    host = 127.0.0.1\n    port = 5055\n    debug = False\n    remote_lookups = false\n\n    [API_KEYS]\n    bitly =\n    macaddress_io =\n    \"\"\").strip() + \"\\n\"\n\n    with tempfile.TemporaryDirectory() as tmp:\n        ini_path = os.path.join(tmp, 'unfurl.ini')\n        with open(ini_path, 'w') as f:\n            f.write(ini_contents)\n\n        env = os.environ.copy()\n        env['PYTHONPATH'] = repo_root\n\n        cmd = [sys.executable, '-c', 'from unfurl.app import web_app; web_app()']\n        proc = subprocess.Popen(\n            cmd,\n            cwd=tmp,\n            env=env,\n            stdout=subprocess.PIPE,\n            stderr=subprocess.PIPE,\n            text=True\n        )\n\n        # Allow server to start and emit logs\n        time.sleep(2)\n        proc.terminate()\n        try:\n            out, err = proc.communicate(timeout=2)\n        except subprocess.TimeoutExpired:\n            proc.kill()\n            out, err = proc.communicate()\n\n        output = (out or \"\") + (err or \"\")\n\n    print(\"\\n[+] Debug mode spawn check\")\n    print(\"    Config: debug = False\")\n\n    if \"Debug mode: on\" in output or \"Debugger is active\" in output:\n        print(\"    ✅ Debug mode is ON despite debug=False (vulnerable)\")\n    else:\n        print(\"    ⚠️  Debug mode not detected in logs (check output below)\")\n\n    if output.strip():\n        print(\"\\n--- server output (truncated) ---\")\n        print(\"\\n\".join(output.splitlines()[:15]))\n        print(\"--- end ---\")\n\n\ndef run_remote_probe(target: str) -> None:\n    import requests\n\n    print(\"\\n[+] Remote debug indicator probe (best-effort)\")\n    print(f\"    Target: {target}\")\n\n    # This app does not easily throw exceptions from user input, so\n    # absence of indicators does NOT prove debug is off.\n    probe_urls = [\n        f\"{target.rstrip('/')}/__nonexistent__\",\n    ]\n\n    detected = False\n    for url in probe_urls:\n        try:\n            resp = requests.get(url, timeout=10)\n            if \"Werkzeug Debugger\" in resp.text or \"Traceback\" in resp.text:\n                detected = True\n                print(\"    ✅ Debug indicators found\")\n                break\n        except Exception as e:\n            print(f\"    ⚠️  Probe failed: {e}\")\n\n    if not detected:\n        print(\"    ⚠️  No debug indicators found (this is not definitive)\")\n\n\ndef main():\n    parser = argparse.ArgumentParser(description='Unfurl debug mode PoC (corrected)')\n    parser.add_argument('--spawn', action='store_true', help='Run local spawn check (default)')\n    parser.add_argument('--target', help='Target Unfurl URL for remote probe')\n    args = parser.parse_args()\n\n    if args.target:\n        run_remote_probe(args.target)\n    else:\n        run_spawn_check()\n\n\nif __name__ == '__main__':\n    main()\n```\n\n### Impact\nIf the service is exposed beyond localhost (bound to 0.0.0.0 or reverse-proxied), an attacker can access the Werkzeug debugger. This can disclose sensitive information and may allow remote code execution if a debugger PIN is obtained. At minimum, stack traces and environment details are exposed on errors.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "dfir-unfurl"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "20250810"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/obsidianforensics/unfurl/security/advisories/GHSA-vg9h-jx4v-cwx2"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/obsidianforensics/unfurl/commit/4c0a07ab1e9af3a1ddf0e7f47153ec9ba77946dd"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/obsidianforensics/unfurl"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-489" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-01-29T15:32:33Z",
    "nvd_published_at" : null
  }
}