(RHSA-2005:025) exim security update

Exim is a mail transport agent (MTA) developed at the University of
Cambridge for use on Unix systems connected to the Internet.

A buffer overflow was discovered in the spa_base64_to_bits function in
Exim, as originally obtained from Samba code. If SPA authentication is
enabled, a remote attacker may be able to exploit this vulnerability to
execute arbitrary code as the ‘exim’ user. The Common Vulnerabilities and
Exposures project (cve.mitre.org) has assigned the name CAN-2005-0022 to
this issue. Please note that SPA authentication is not enabled by default
in Red Hat Enterprise Linux 4.

Buffer overflow flaws were discovered in the host_aton and
dns_build_reverse functions in Exim. A local user can trigger these flaws
by executing exim with carefully crafted command line arguments and may be
able to gain the privileges of the ‘exim’ account. The Common
Vulnerabilities and Exposures project (cve.mitre.org) has assigned the name
CAN-2005-0021 to this issue.

Users of Exim are advised to update to these erratum packages which contain
backported patches to correct these issues.