CVE-2026-3709: Simple Flight Ticket Booking SQLI Flaw

CVE-2026-3709 Overview

A SQL Injection vulnerability has been identified in code-projects Simple Flight Ticket Booking System version 1.0. The vulnerability affects the /register.php file, where manipulation of the Username argument can lead to SQL injection attacks. This weakness allows remote attackers to potentially execute arbitrary SQL commands against the backend database, compromising data integrity and confidentiality.

Critical Impact

Remote attackers can exploit this SQL injection vulnerability to bypass authentication, extract sensitive data, modify database contents, or potentially gain unauthorized access to the underlying system through the publicly accessible registration endpoint.

Affected Products

• Carmelo Simple Flight Ticket Booking System 1.0
• code-projects Simple Flight Ticket Booking System 1.0

Discovery Timeline

• 2026-03-08 - CVE-2026-3709 published to NVD
• 2026-03-09 - Last updated in NVD database

Technical Details for CVE-2026-3709

Vulnerability Analysis

This SQL Injection vulnerability exists in the user registration functionality of the Simple Flight Ticket Booking System. The /register.php endpoint fails to properly sanitize or parameterize user-supplied input in the Username field before incorporating it into SQL queries. When a user submits registration data, the application directly concatenates the Username value into database queries without adequate input validation or prepared statements.

The vulnerability is classified under CWE-89 (SQL Injection) and CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component). The attack can be initiated remotely without authentication, as the registration page is publicly accessible. An exploit has been disclosed publicly, increasing the risk of active exploitation attempts.

Root Cause

The root cause of this vulnerability is improper input validation and lack of parameterized queries in the /register.php file. The application directly incorporates user-supplied Username data into SQL statements without proper sanitization, escaping, or the use of prepared statements. This fundamental secure coding oversight allows attackers to inject malicious SQL syntax that gets executed by the database engine.

Attack Vector

The attack vector for CVE-2026-3709 is network-based and requires no authentication or user interaction. An attacker can craft malicious HTTP requests to the /register.php endpoint, embedding SQL injection payloads in the Username parameter. The vulnerability can be exploited through standard web request manipulation using tools like Burp Suite, cURL, or custom scripts.

The exploitation process involves submitting specially crafted input containing SQL metacharacters and commands through the Username field during the registration process. Successful exploitation could allow attackers to extract database contents, bypass authentication mechanisms, modify or delete data, or potentially execute system commands depending on database configuration and privileges.

Detection Methods for CVE-2026-3709

Indicators of Compromise

• Unusual or malformed requests to /register.php containing SQL syntax such as single quotes, UNION statements, or comment sequences
• Database error messages appearing in HTTP responses or logs indicating SQL syntax errors
• Multiple rapid registration attempts from single IP addresses with varying payload patterns
• Anomalous database queries in database logs showing unexpected SELECT, UNION, or data extraction operations

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect SQL injection patterns in request parameters targeting the registration endpoint
• Monitor application logs for SQL error messages or unexpected database exceptions originating from /register.php
• Deploy intrusion detection signatures for common SQL injection attack patterns including UNION-based, error-based, and time-based blind injection techniques
• Analyze web server access logs for suspicious patterns in POST requests to the registration functionality

Monitoring Recommendations

• Enable detailed logging for all database queries executed by the application to identify injection attempts
• Configure alerts for HTTP 500 errors or database connection failures associated with the registration workflow
• Implement rate limiting and anomaly detection on the /register.php endpoint to identify automated attack attempts
• Monitor for data exfiltration indicators such as unusually large response sizes or out-of-band DNS queries

How to Mitigate CVE-2026-3709

Immediate Actions Required

• Restrict access to the vulnerable /register.php endpoint through IP whitelisting or temporary disabling if registration functionality is not critical
• Deploy a Web Application Firewall with SQL injection protection rules in blocking mode
• Review and audit all user input handling in the application, particularly in authentication and registration functions
• Consider taking the application offline until proper remediation can be implemented if handling sensitive data

Patch Information

No official vendor patch is currently available for this vulnerability. The affected software is a code-projects educational or demonstration application. Organizations using this software should implement the workarounds below and consider migrating to a more actively maintained booking system solution. For additional technical details, refer to the GitHub CVE Issue Discussion and VulDB #349655.

Workarounds

• Implement prepared statements with parameterized queries for all database interactions in the /register.php file
• Add input validation to whitelist acceptable characters for the Username field, rejecting special characters used in SQL injection
• Deploy a reverse proxy or WAF to filter malicious requests before they reach the application
• Apply the principle of least privilege to the database user account used by the application, limiting its permissions to only necessary operations

The recommended approach is to refactor the vulnerable code to use prepared statements. In PHP, this involves using PDO or MySQLi with bound parameters instead of directly concatenating user input into SQL query strings. All user-supplied data should be treated as untrusted and validated against expected formats before processing.