Compiler Engineer Dan Gohman of Google discovered a flaw in the JavaScript engine where memory was being incorrectly allocated for some functions and the calls for allocations were not always properly checked for overflow, leading to potential buffer overflows. When combined with other vulnerabilities, these flaws could be potentially exploitable.
In general this flaw cannot be exploited through email in the Thunderbird and Seamonkey products because scripting is disabled, but is potentially a risk in browser or browser-like contexts.
Vulmon