Low: xinetd (SL6)

Synopsis: Low: xinetd security and bug fix update
Issue Date: 2013-02-21
CVE Numbers: CVE-2012-0862

When xinetd services are configured with the “TCPMUX” or “TCPMUXPLUS” type, and
the tcpmux-server service is enabled, those services are accessible via port 1.
It was found that enabling the tcpmux-server service (it is disabled by
default) allowed every xinetd service, including those that are not configured
with the “TCPMUX” or “TCPMUXPLUS” type, to be accessible via port 1. This could
allow a remote attacker to bypass intended firewall restrictions.

This update also fixes the following bugs:

* Prior to this update, a file descriptor array in the service.c source file
was not handled as expected. As a consequence, some of the descriptors remained
open when xinetd was under heavy load. Additionally, the system log was filled
with a large number of messages that took up a lot of disk space over time.
This update modifies the xinetd code to handle the file descriptors correctly
and messages no longer fill the system log.

* Prior to this update, services were disabled permanently when their CPS limit
was reached. As a consequence, a failed bind operation could occur when xinetd
attempted to restart the service. This update adds additional logic that
attempts to restart the service. Now, the service is only disabled if xinetd
cannot restart the service after 30 attempts.


– Scientific Linux Development Team