CVE-2006-0883

Because OpenSSH and OpenPAM have conflicting designs (one is event-driven while the other is callback-driven), it is necessary for OpenSSH to fork a child process to handle calls to the PAM framework. However, if the unprivileged child terminates while PAM authentication is under way, the parent process incorrectly believes that the PAM child also terminated. The parent process then terminates, and the PAM child is left behind. Due to the way OpenSSH performs internal accounting, these orphaned PAM children are counted as pending connections by the master OpenSSH server process. Once a certain number of orphans has accumulated, the master decides that it is overloaded and stops accepting client connections.