Mozilla Foundation Security Advisory 2008-18

Java socket connection to any local port via LiveConnect

March 25, 2008
Gregory Fleischer
Firefox, SeaMonkey
Fixed in
  • Firefox
  • SeaMonkey 1.1.9


Security researcher Gregory Fleischer demonstrated that web content fetched via the jar: protocol can use Java via LiveConnect to open socket connections to arbitrary ports on the user's machine ("localhost"). The issue is caused by improper parsing of the content origin passed from the browser to the Java plugin. Such content was incorrectly evaluated to have a null host, assumed to be a local file, and was subsequently allowed permission to connect to the localhost. Sun has updated the Java Runtime Environment with a fix for this problem. Mozilla has also added a fix to LiveConnect to protect users who don't have the latest version of Java.


Disable Java until a version containing fixes can be installed or upgrade your system's JRE to one of the fixed versions listed in Sun's advisory: 1.6.0_05, 1.5.0_15, and 1.4.2_17.