pop3d contains a flaw that allows a malicious user to access arbitrary mail files. The issue is triggered due to the usage of mktmp() in order to create temporary files in /tmp. A local attacker can use this to read the mail currently being processed by the pop3d daemon. This flaw may lead to a loss of confidentiality.
Upgrade to Slackware 3.1 or higher, as it has been reported to fix this vulnerability. An upgrade is required as there are no known workarounds.