Gibbon through 26.0.00 allows /modules/School%20Admin/messengerSettings.php Server Side Template Injection leading to Remote Code Execution because input is passed to the Twig template engine (messengerSettings.php) without sanitization.
The product uses a template engine to insert or process externally-influenced input, but it does not neutralize or incorrectly neutralizes special elements or syntax that can be interpreted as template expressions or other code directives when processed by the engine.