Mozilla developer Boris Zbarsky reported reported a problem where jsval-returning quickstubs fail to wrap their return values, causing a compartment mismatch. This mismatch can cause garbage collection to occur incorrectly and lead to a potentially exploitable crash.
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.
Vulmon