The remote host is missing an update to the system as announced in the referenced advisory.
Update your system with the appropriate patches or software upgrades. http://www.mozilla.org/security/announce/2011/mfsa2011-11.html http://www.vuxml.org/freebsd/b2f09169-55af-11e0-9d6f-000f20797ede.html
The following packages are affected: firefox libxul linux-firefox linux-firefox-devel linux-seamonkey seamonkey
CVSS Base Score: 3.3