The remote host is missing an update to mozilla-firefox announced via advisory DSA 837-1. Tom Ferris discovered a bug in the IDN hostname handling of Mozilla Firefox, which is also present in the other browsers from the same family that allows remote attackers to cause a denial of service and possibly execute arbitrary code via a hostname with dashes.

For the stable distribution (sarge) this problem has been fixed in version 1.0.4-2sarge4. For the unstable distribution (sid) this problem has been fixed in version 1.0.6-5. We recommend that you upgrade your mozilla-firefox package. https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20837-1