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
| #!/usr/bin/env python3
"""
CVE-2026-39842 - OpenRemote Expression Injection Detection Script
=================================================================
Detects OpenRemote instances vulnerable to CVE-2026-39842 (CVSS 10.0)
Expression injection in Rules Engine via unsandboxed Nashorn ScriptEngine.eval()
Affected: OpenRemote <= 1.21.0
Fixed: OpenRemote >= 1.22.0
Detection Method:
1. Fingerprints OpenRemote via known API endpoints and response patterns
2. Extracts version information from /api/master/info or HTML meta tags
3. Checks if the rules API endpoint is accessible
4. Compares detected version against the fixed version (1.22.0)
Author: @kerattin
Date: 2026-04-16
License: MIT
"""
import argparse
import json
import re
import sys
import urllib.request
import urllib.error
import ssl
from typing import Optional, Tuple
# ANSI color codes
class Colors:
RED = "\033[91m"
GREEN = "\033[92m"
YELLOW = "\033[93m"
BLUE = "\033[94m"
MAGENTA = "\033[95m"
CYAN = "\033[96m"
BOLD = "\033[1m"
RESET = "\033[0m"
BANNER = f"""{Colors.CYAN}{Colors.BOLD}
___ ____ _____ _ _ ____ _____ __ __ ___ _____ _____
/ _ \\| _ \\| ____| \\ | | _ \\| ____| \\/ |/ _ \\_ _| ____|
| | | | |_) | _| | \\| | |_) | _| | |\\/| | | | || | | _|
| |_| | __/| |___| |\\ | _ <| |___| | | | |_| || | | |___
\\___/|_| |_____|_| \\_|_| \\_\\_____|_| |_|\\___/ |_| |_____|
CVE-2026-39842 Detection Script
Expression Injection in Rules Engine (CVSS 10.0)
{Colors.RESET}"""
FIXED_VERSION = (1, 22, 0)
TIMEOUT = 10
def parse_version(version_str: str) -> Optional[Tuple[int, ...]]:
"""Parse a version string like '1.21.0' into a tuple of integers."""
match = re.search(r"(\d+)\.(\d+)\.(\d+)", version_str)
if match:
return tuple(int(x) for x in match.groups())
match = re.search(r"(\d+)\.(\d+)", version_str)
if match:
return tuple(int(x) for x in match.groups()) + (0,)
return None
def make_request(url: str, timeout: int = TIMEOUT, method: str = "GET") -> Tuple[Optional[int], Optional[str], dict]:
"""Make an HTTP request and return (status_code, body, headers)."""
ctx = ssl.create_default_context()
ctx.check_hostname = False
ctx.verify_mode = ssl.CERT_NONE
try:
req = urllib.request.Request(url, method=method)
req.add_header("User-Agent", "CVE-2026-39842-Scanner/1.0")
req.add_header("Accept", "application/json, text/html, */*")
resp = urllib.request.urlopen(req, timeout=timeout, context=ctx)
body = resp.read().decode("utf-8", errors="replace")
headers = dict(resp.headers)
return resp.status, body, headers
except urllib.error.HTTPError as e:
body = ""
try:
body = e.read().decode("utf-8", errors="replace")
except Exception:
pass
return e.code, body, dict(e.headers) if e.headers else {}
except Exception:
return None, None, {}
def detect_openremote(target: str) -> dict:
"""
Detect if target is running OpenRemote and check vulnerability status.
Returns a dict with:
- is_openremote: bool
- version: str or None
- version_tuple: tuple or None
- is_vulnerable: bool or None (None if version unknown)
- rules_api_accessible: bool
- details: str
- evidence: list of strings
"""
result = {
"target": target,
"is_openremote": False,
"version": None,
"version_tuple": None,
"is_vulnerable": None,
"rules_api_accessible": False,
"js_rules_enabled": None,
"details": "",
"evidence": [],
}
# Normalize target URL
if not target.startswith("http"):
target = f"https://{target}"
target = target.rstrip("/")
# ---- Step 1: Check /api/master/info endpoint ----
info_url = f"{target}/api/master/info"
status, body, headers = make_request(info_url)
if status == 200 and body:
try:
info = json.loads(body)
result["is_openremote"] = True
result["evidence"].append(f"API info endpoint responded: {info_url}")
# Version from info response
version = info.get("version", info.get("appVersion", ""))
if version:
result["version"] = version
result["version_tuple"] = parse_version(version)
result["evidence"].append(f"Version from API: {version}")
except json.JSONDecodeError:
# Might still be OpenRemote with non-JSON response
if "openremote" in body.lower():
result["is_openremote"] = True
result["evidence"].append("OpenRemote keyword found in info endpoint response")
# ---- Step 2: Check main page for OpenRemote fingerprints ----
if not result["is_openremote"]:
status, body, headers = make_request(target)
if status and body:
openremote_indicators = [
"openremote",
"OpenRemote",
"or-app",
"or-header",
"or-realm-picker",
"/manager/",
"keycloak.js",
]
for indicator in openremote_indicators:
if indicator in body:
result["is_openremote"] = True
result["evidence"].append(f"Fingerprint '{indicator}' found in main page")
break
# Try to extract version from HTML
ver_match = re.search(r"openremote[/\-]?v?(\d+\.\d+\.\d+)", body, re.IGNORECASE)
if ver_match:
result["version"] = ver_match.group(1)
result["version_tuple"] = parse_version(ver_match.group(1))
result["evidence"].append(f"Version from HTML: {ver_match.group(1)}")
# ---- Step 3: Check /swagger endpoint for API docs ----
if not result["is_openremote"]:
swagger_url = f"{target}/swagger"
status, body, headers = make_request(swagger_url)
if status and body and "openremote" in body.lower():
result["is_openremote"] = True
result["evidence"].append("OpenRemote found in Swagger docs")
if not result["is_openremote"]:
result["details"] = "Target does not appear to be running OpenRemote"
return result
# ---- Step 4: Check rules API accessibility ----
rules_endpoints = [
f"{target}/api/master/rules/realm",
f"{target}/api/master/rules",
]
for rules_url in rules_endpoints:
status, body, headers = make_request(rules_url)
if status in (200, 401, 403):
result["rules_api_accessible"] = True
result["evidence"].append(f"Rules API endpoint reachable: {rules_url} (HTTP {status})")
if status == 200 and body:
try:
rules_data = json.loads(body)
if isinstance(rules_data, list):
for rule in rules_data:
lang = rule.get("lang", "").upper()
if lang == "JAVASCRIPT":
result["js_rules_enabled"] = True
result["evidence"].append("JavaScript rules found in rules listing")
break
except (json.JSONDecodeError, TypeError):
pass
break
# ---- Step 5: Determine vulnerability status ----
if result["version_tuple"]:
if result["version_tuple"] < FIXED_VERSION:
result["is_vulnerable"] = True
result["details"] = (
f"VULNERABLE: OpenRemote {result['version']} is below the fixed version 1.22.0. "
f"The Nashorn ScriptEngine.eval() executes user-supplied JavaScript rules without "
f"sandboxing or ClassFilter restrictions. Any user with write:rules role can achieve "
f"RCE as root via Java.type() reflection."
)
else:
result["is_vulnerable"] = False
result["details"] = (
f"NOT VULNERABLE: OpenRemote {result['version']} >= 1.22.0. "
f"JavaScript rules have been deprecated and removed in this version."
)
else:
result["is_vulnerable"] = None
result["details"] = (
"OpenRemote detected but version could not be determined. "
"Manual verification recommended. Check if version <= 1.21.0."
)
return result
def print_result(result: dict, verbose: bool = False) -> None:
"""Pretty-print detection results."""
target = result["target"]
print(f"\n{Colors.BOLD}Target:{Colors.RESET} {target}")
print(f"{'=' * 60}")
if not result["is_openremote"]:
print(f"{Colors.BLUE}[INFO]{Colors.RESET} Not an OpenRemote instance")
return
print(f"{Colors.GREEN}[+]{Colors.RESET} OpenRemote instance detected")
if result["version"]:
print(f"{Colors.GREEN}[+]{Colors.RESET} Version: {result['version']}")
if result["rules_api_accessible"]:
print(f"{Colors.YELLOW}[!]{Colors.RESET} Rules API endpoint is reachable")
if result["js_rules_enabled"]:
print(f"{Colors.RED}[!]{Colors.RESET} JavaScript rules are active on this instance")
if result["is_vulnerable"] is True:
print(f"\n{Colors.RED}{Colors.BOLD}[VULNERABLE]{Colors.RESET} {result['details']}")
print(f"\n{Colors.YELLOW}Vulnerability Details:{Colors.RESET}")
print(f" CVE: CVE-2026-39842")
print(f" CVSS: 10.0 (Critical)")
print(f" CWE: CWE-94 (Code Injection), CWE-917 (EL Injection)")
print(f" Attack Vector: Network / Low Privileges (write:rules)")
print(f" Impact: RCE as root, file read, credential theft, tenant bypass")
print(f" Fix: Upgrade to OpenRemote >= 1.22.0")
elif result["is_vulnerable"] is False:
print(f"\n{Colors.GREEN}{Colors.BOLD}[NOT VULNERABLE]{Colors.RESET} {result['details']}")
else:
print(f"\n{Colors.YELLOW}{Colors.BOLD}[UNKNOWN]{Colors.RESET} {result['details']}")
if verbose and result["evidence"]:
print(f"\n{Colors.CYAN}Evidence:{Colors.RESET}")
for ev in result["evidence"]:
print(f" - {ev}")
def main():
global TIMEOUT
parser = argparse.ArgumentParser(
description="CVE-2026-39842 - OpenRemote Expression Injection Detection Script",
epilog="Example: python3 detect_openremote.py -t https://demo.openremote.io",
)
parser.add_argument(
"-t", "--target",
help="Single target URL or IP (e.g., https://demo.openremote.io)",
)
parser.add_argument(
"-l", "--list",
help="File containing list of targets (one per line)",
)
parser.add_argument(
"-o", "--output",
help="Output results to JSON file",
)
parser.add_argument(
"-v", "--verbose",
action="store_true",
help="Show detailed evidence for each finding",
)
parser.add_argument(
"--timeout",
type=int,
default=TIMEOUT,
help=f"HTTP request timeout in seconds (default: {TIMEOUT})",
)
parser.add_argument(
"--no-banner",
action="store_true",
help="Suppress the banner",
)
args = parser.parse_args()
if not args.target and not args.list:
parser.print_help()
sys.exit(1)
if not args.no_banner:
print(BANNER)
TIMEOUT = args.timeout
targets = []
if args.target:
targets.append(args.target)
if args.list:
try:
with open(args.list, "r") as f:
for line in f:
line = line.strip()
if line and not line.startswith("#"):
targets.append(line)
except FileNotFoundError:
print(f"{Colors.RED}[ERROR]{Colors.RESET} File not found: {args.list}")
sys.exit(1)
all_results = []
vulnerable_count = 0
total_openremote = 0
for target in targets:
result = detect_openremote(target)
all_results.append(result)
print_result(result, verbose=args.verbose)
if result["is_openremote"]:
total_openremote += 1
if result["is_vulnerable"]:
vulnerable_count += 1
# Summary
print(f"\n{'=' * 60}")
print(f"{Colors.BOLD}Scan Summary{Colors.RESET}")
print(f" Targets scanned: {len(targets)}")
print(f" OpenRemote found: {total_openremote}")
print(f" Vulnerable: {Colors.RED}{vulnerable_count}{Colors.RESET}")
print(f" Not vulnerable: {total_openremote - vulnerable_count}")
# JSON output
if args.output:
with open(args.output, "w") as f:
json.dump(all_results, f, indent=2, default=str)
print(f"\n{Colors.GREEN}[+]{Colors.RESET} Results saved to {args.output}")
if __name__ == "__main__":
main()
|
