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/mfsa2011-19.html http://www.mozilla.org/security/announce/2011/mfsa2011-20.html http://www.mozilla.org/security/announce/2011/mfsa2011-21.html http://www.mozilla.org/security/announce/2011/mfsa2011-22.html http://www.mozilla.org/security/announce/2011/mfsa2011-23.html http://www.mozilla.org/security/announce/2011/mfsa2011-24.html http://www.mozilla.org/security/announce/2011/mfsa2011-25.html http://www.mozilla.org/security/announce/2011/mfsa2011-26.html http://www.mozilla.org/security/announce/2011/mfsa2011-27.html http://www.mozilla.org/security/announce/2011/mfsa2011-28.html http://www.vuxml.org/freebsd/dfe40cff-9c3f-11e0-9bec-6c626dd55a41.html

The following packages are affected: firefox linux-firefox thunderbird linux-thunderbird