The remote host is missing an update to xulrunner-1.9 announced via advisory USN-765-1.

The problem can be corrected by upgrading your system to the following package versions: Ubuntu 8.04 LTS: firefox-3.0 3.0.10+nobinonly-0ubuntu0.8.04.1 xulrunner-1.9 1.9.0.10+nobinonly-0ubuntu0.8.04.1 Ubuntu 8.10: abrowser 3.0.10+nobinonly-0ubuntu0.8.10.1 firefox-3.0 3.0.10+nobinonly-0ubuntu0.8.10.1 xulrunner-1.9 1.9.0.10+nobinonly-0ubuntu0.8.10.1 Ubuntu 9.04: abrowser 3.0.10+nobinonly-0ubuntu0.9.04.1 firefox-3.0 3.0.10+nobinonly-0ubuntu0.9.04.1 xulrunner-1.9 1.9.0.10+nobinonly-0ubuntu0.9.04.1 After a standard system upgrade you need to restart Firefox and any applications that use xulrunner, such as Epiphany, to effect the necessary changes. https://secure1.securityspace.com/smysecure/catid.html?in=USN-765-1

It was discovered that the upstream security fixes in USN-764-1 introduced a regression which could cause the browser to crash. If a user were tricked into viewing a malicious website, a remote attacker could cause a denial of service or possibly execute arbitrary code with the privileges of the user invoking the program.