Security researcher miaubiz used the Address Sanitizer tool to discover a buffer overflow in Canvas when specific bad height and width values were given through HTML. This could lead to a potentially exploitable crash.
Miaubiz also found a potentially exploitable crash when 2D and 3D content was mixed which was introduced during Firefox development and fixed before general release.
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