Chamilo LMS: SQL Injection in the statistics AJAX endpoint

Chamilo LMS is a learning management system. Version 1.11.34 and prior contains a SQL Injection vulnerability in the statistics AJAX endpoint. The parameters date_start and date_end from $_REQUEST are embedded directly into a raw SQL string without proper sanitization. Although Database::escape_string() is called downstream, its output is immediately neutralized by str_replace("\'", "'", ...), which restores any injected single quotes — effectively bypassing the escaping mechanism entirely. This allows an authenticated attacker to inject arbitrary SQL statements into the database query, enabling blind time-based and conditional data extraction. This issue has been patched in version 1.11.36.