The Apache web server must set an inactive timeout for sessions.

Leaving sessions open indefinitely is a major security risk. An attacker can easily use an already authenticated session to access the hosted application as the previously authenticated user. By closing sessions after a set period of inactivity, the Apache web server can make certain that those sessions that are not closed through the user logging out of an application are eventually closed. mod_reqtimeout is an Apache module designed to shut down connections from clients taking too long to send their request, as seen in many attacks. This module provides a directive that allows Apache to close the connection if it senses that the client is not sending data quickly enough. Acceptable values are 5 minutes for high-value applications, 10 minutes for medium-value applications, and 20 minutes for low-value applications.