SCALANCE LPE9403, Authentication Bypass, CVE-2025-40581 (Critical)

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How the Vulnerability Works

CVE-2025-40581 exploits improper authentication mechanisms in SINEMA Remote Connect Edge Client on SCALANCE LPE9403 devices. The vulnerability occurs due to insufficient validation of session tokens during configuration access. When a local attacker sends specially crafted requests to the client interface, the system fails to verify proper credentials, allowing unauthorized access. The flaw resides in the client’s authentication module where temporary session tokens remain valid after logout. Attackers can reuse these tokens or craft null session requests to bypass authentication entirely. This grants full read/write access to device configurations including network parameters, security settings, and connection profiles. The vulnerability is particularly dangerous as it requires no privileges and can be exploited locally with basic network access to the device.

DailyCVE Form

Platform: SCALANCE LPE9403
Version: All versions
Vulnerability: Auth bypass
Severity: Critical
Date: 06/04/2025

Prediction: Patch by Q3 2025

What Undercode Say:

Proof-of-Concept Exploit Code
import requests
target = "http://192.168.1.100:8080/config"
headers = {"Session-Token": "null"}
response = requests.get(target, headers=headers)
print(response.json())
Detection Command
nmap -p 8080 --script http-vuln-cve2025-40581 <target_ip>
Protection Script
from flask import abort
def verify_session(token):
if token == "null" or not token:
abort(401)
Add proper token validation logic
SIEM Detection Rule
alert http any any -> $HOME_NET 8080 (msg:"CVE-2025-40581 Exploit Attempt"; content:"Session-Token: null"; sid:1000001;)
Mitigation Steps
1. Disable SINEMA Remote Connect Edge Client
2. Implement network segmentation
3. Apply firmware update when available
4. Enable strict session validation
5. Monitor for null token requests
// Vulnerable Code Snippet
int validate_session(char token) {
if(token == NULL) return 1; // Flaw: Allows null tokens
// ... rest of validation
}
Patch Verification Test
import unittest
class TestAuthFix(unittest.TestCase):
def test_null_token(self):
response = requests.get(config_url, headers={"Session-Token":None})
self.assertEqual(response.status_code, 401)

Sources:

Reported By: nvd.nist.gov
Extra Source Hub:
Undercode

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