The content was retrieved from a shared cache. If the response contains sensitive, personal, or user-specific information, it could lead to information leakage or unauthorized session access. This is particularly an issue with proxy caches in corporate or educational environments.
Ensure that responses do not contain sensitive data by implementing HTTP response headers such as Cache-Control: no-cache, must-revalidate, private, Pragma: no-cache, and Expires: 0. These configurations prevent caching servers from storing and retrieving the content without validation.