Critical SQL Injection Vulnerability Exposed in Ruby on Rails Controller

A critical SQL injection vulnerability has been identified within a Ruby on Rails application, exposing a direct path for attackers to execute arbitrary database commands. The flaw is located in a single file but carries a high severity rating, directly linked to the OWASP Top 10's 'Injection' category. The vulnerability stems from the unsafe concatenation of user input into an SQL query, a fundamental security failure that bypasses standard sanitization defenses.

The specific exposure is in the `app/controllers/users_controller.rb` file at line 29. The code constructs a database query by directly interpolating the `params[:user][:id]` value into the SQL string (`User.where("id = '#{params[:user][:id]}'")[0]`). This pattern allows a malicious actor to manipulate the `id` parameter to inject and run unintended SQL commands, potentially leading to data theft, corruption, or complete system compromise. The automated security scan reports an 80% confidence level in this finding, classifying it under CWE-89.

This discovery places immediate pressure on the development and security teams to remediate the flaw. The standard and urgent recommendation is to refactor the code to use parameterized queries or prepared statements, which separate data from commands. Failure to patch this vulnerability leaves the application's database—and by extension, user data and system integrity—under active risk of exploitation. The finding serves as a stark reminder of the persistent threat posed by basic injection flaws in even modern web frameworks.