A vulnerability has been found and corrected in postfix:

The SMTP server in Postfix before 2.5.13, 2.6.x before 2.6.10,
2.7.x before 2.7.4, and 2.8.x before 2.8.3, when certain Cyrus SASL
authentication methods are enabled, does not create a new server handle
after client authentication fails, which allows remote attackers to
cause a denial of service (heap memory corruption and daemon crash)
or possibly execute arbitrary code via an invalid AUTH command
with one method followed by an AUTH command with a different method
(CVE-2011-1720).

Packages for 2009.0 are provided as of the Extended Maintenance
Program. Please visit this link to learn more:
http://store.mandriva.com/product_info.php?cPath=149&products_id=490

The updated packages have been patched to correct this issue.