Improper Handling of Exceptional Conditions

Summary

The package react-router is a routing library for React applications. In versions 7.2.x prior to 7.5.2, forcing an application into SPA mode was possible by adding a specific header to the request. If the application utilizes SSR and is coerced into SPA mode, this could lead to an error that completely disrupts the page. Furthermore, if a caching system is in place, this error response could be cached, resulting in cache poisoning that significantly impacts the application's availability.