The CESG, the Information Security Arm of GCHQ, reported a dangling pointer dereference within the Netscape Plugin Application Programming Interface (NPAPI) that could lead to the NPAPI subsystem crashing. This issue requires a maliciously crafted NPAPI plugin in concert with scripted web content, resulting in a potentially exploitable crash when triggered.
In general this flaw cannot be exploited through email in the Thunderbird product because scripting is disabled, but is potentially a risk in browser or browser-like contexts.
Vulmon