Sendmail is a Mail Transport Agent (MTA) used to send mail between machines.
A flaw in the handling of asynchronous signals was discovered in Sendmail. A remote attacker may be able to exploit a race condition to execute arbitrary code as root. The Common Vulnerabilities and Exposures project assigned the name CVE-2006-0058 to this issue.
By default on Red Hat Enterprise Linux 3 and 4, Sendmail is configured to only accept connections from the local host. Therefore, only users who have configured Sendmail to listen to remote hosts would be able to be remotely exploited by this vulnerability.
Users of Sendmail are advised to upgrade to these erratum packages, which contain a backported patch from the Sendmail team to correct this issue.