CamaleonCMS 2.9.1 Server-Side Template Injection via test_email Action

CamaleonCMS 2.9.1 contains a server-side template injection vulnerability that allows authenticated administrators to execute arbitrary commands by embedding ERB tags in the email parameter of the test_email settings action, which are evaluated when an SMTP rejection reflects the recipient address back in the exception message rendered as an inline ERB template. Attackers can submit a crafted email parameter containing ERB expressions through the admin settings test_email endpoint, causing the Rails inline template renderer to evaluate attacker-controlled Ruby code and achieve arbitrary command execution as the Rails process user.