Summary
The remote host is missing an update as announced
via advisory SSA:2010-090-02.
Solution
https://secure1.securityspace.com/smysecure/catid.html?in=SSA:2010-090-02
Insight
New mozilla-firefox packages are available for Slackware 13.0 and -current to fix security issues.
More details about the issues may be found on the Mozilla website:
http://www.mozilla.org/security/known-vulnerabilities/firefox36.html