CVE-2025-27539: SQL Injection Vulnerability in TeleControl Server Basic

Overview

The cybersecurity landscape is under constant threat from various vulnerabilities. One such vulnerability that poses a significant risk to the security of computer systems is CVE-2025-27539. This vulnerability affects all versions of TeleControl Server Basic below version V3.1.2.2. This vulnerability is particularly concerning because it enables an unauthenticated remote attacker to bypass authorization controls, read from, and write to the application’s database and execute code with “NT AUTHORITYNetworkService” permissions.
Given the widespread use of TeleControl Server Basic across various organizations, this vulnerability, if exploited, could potentially lead to a system compromise or data leakage. Therefore, understanding the nature of this vulnerability, how it works, and the steps that can be taken to mitigate it is essential for all cybersecurity professionals and system administrators.

Vulnerability Summary

CVE ID: CVE-2025-27539
Severity: Critical (9.8 CVSS Score)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Potential system compromise, data leakage

Affected Products

Product | Affected Versions

TeleControl Server Basic | All versions < V3.1.2.2 How the Exploit Works

The vulnerability is a result of the application’s improper handling of user-supplied input in the ‘VerifyUser’ method. An attacker can exploit this vulnerability by sending specially crafted SQL statements, which are passed to the application’s database. This allows the attacker to manipulate the SQL queries to extract data from the database, modify the data, or execute arbitrary code with “NT AUTHORITYNetworkService” permissions.

Conceptual Example Code

Below is a conceptual example of how an attacker might exploit this vulnerability using an HTTP request:

POST /VerifyUser HTTP/1.1
Host: vulnerablehost:8000
Content-Type: application/json
{ "username": "admin'; DROP TABLE users;--" }

In this example, the attacker sends a malicious SQL statement as part of the ‘username’ parameter. This SQL statement is designed to drop the ‘users’ table from the application’s database.

Mitigation Guidance

To mitigate this vulnerability, users are advised to apply the vendor patch V3.1.2.2. As a temporary mitigation, users can use a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) to detect and prevent SQL injection attacks. It is also highly recommended to follow the principle of least privilege. Ensure that any account that can access the ‘VerifyUser’ method does not have more privileges than it needs to perform its intended function.