The remote host is missing an update as announced via advisory SSA:2009-352-01.

https://secure1.securityspace.com/smysecure/catid.html?in=SSA:2009-352-01

New seamonkey packages are available for Slackware 12.2, 13.0, and -current to fix security issues. More details about the issues may be found on the Mozilla web site: http://www.mozilla.org/security/known-vulnerabilities/seamonkey20.html