The LiveConnect implementation in plugin/icedteanp/IcedTeaNPPlugin.cc in IcedTea-Web before 1.4.2 allows local users to read the messages between a Java applet and a web browser by pre-creating a temporary socket file with a predictable name in /tmp.

The web browser plug-in in IcedTea-Web 1.0.x before 1.0.6 and 1.1.x before 1.1.4 allows remote attackers to bypass the Same Origin Policy (SOP) and execute arbitrary script or establish network connections to unintended hosts via an applet whose origin has the same second-level domain, but a different sub-domain than the targeted domain.

The IcedTea-Web plugin before 1.2.3 and 1.3.x before 1.3.2 allows remote attackers to execute arbitrary code via a crafted file that validates as both a GIF and a Java JAR file, aka "GIFAR."

The IcedTea-Web plugin before 1.2.3 and 1.3.x before 1.3.2 uses the same class loader for applets with the same codebase path but from different domains, which allows remote attackers to obtain sensitive information or possibly alter other applets via a crafted applet.