🔒 Session Fixation Vulnerability Exposed in arubis/sample_rails_app Rails Code

A critical session management flaw has been flagged in a live Ruby on Rails application, exposing a potential pathway for attackers to hijack user sessions. The automated security scan identified a Broken Authentication vulnerability in the `app/helpers/sessions_helper.rb` file, specifically on line 5 where the code sets `session[:user_id] = user.id` without regenerating the session ID. This omission creates a classic session fixation risk, where an attacker could force a user to authenticate with a known session identifier, granting them unauthorized access to the user's account.

The vulnerability, classified under CWE-384 and OWASP's A07:2021 (Identification and Authentication Failures), was discovered in the `master` branch of the `arubis/sample_rails_app` repository. With a scanner confidence level of 80%, this MEDIUM severity finding points to a direct failure to follow fundamental security best practices for session handling in web applications. The issue is isolated to a single file but represents a systemic authentication failure that could compromise the entire application's security posture.

While the finding is currently a static code analysis result, its presence in a main development branch signals a significant oversight in the application's security lifecycle. If left unaddressed, this flaw could be exploited to bypass authentication controls, leading to data breaches and unauthorized actions. The recommendation is an immediate code review and implementation of session regeneration after successful login, a standard mitigation for this well-documented attack vector.