The PHP package in Slackware 8.1, 9.0, and 9.1, when linked against a static library, includes /tmp in the search path, which allows local users to execute arbitrary code as the PHP user by inserting shared libraries into the appropriate path.
https://exchange.xforce.ibmcloud.com/vulnerabilities/16310
http://www.slackware.com/security/viewer.php?l=slackware-security&y=2004&m=slackware-security.419765