The remote host is missing an update as announced via advisory SSA:2007-222-04.

https://secure1.securityspace.com/smysecure/catid.html?in=SSA:2007-222-04

New seamonkey packages are available for Slackware 11.0 and 12.0 to fix various security issues. For more information, see: http://www.mozilla.org/projects/security/known-vulnerabilities.html#seamonkey