Vulnerability Instance

Security researcher pa_kt reported a flaw via TippingPoint's Zero Day Initiative that an integer overflow is possible when calculating the length for a Javascript string concatenation, which is then used for memory allocation. This results in a buffer overflow, leading to a potentially exploitable memory corruption.
In general these flaws cannot be exploited through email in the Thunderbird and SeaMonkey products because scripting is disabled, but are potentially a risk in browser or browser-like contexts in those products.