Here are the details from the Slackware 10.1 ChangeLog:
patches/packages/zlib-1.2.2-i486-2.tgz: Patched an overflow in zlib that could cause applications using zlib to crash. The overflow does not involve user supplied data, and therefore does not allow the execution of arbitrary code. However, it could still be used by a remote attacker to create a denial of service.
For more information, see: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-2096
(* Security fix *)
You can use the Slackware package browser to obtain an updated version of this package for your Slackware installation. Lazier and smarter people like me will use updating tools such as Swaret or slapt-get 🙂