Using the Address Sanitizer tool, security researcher Atte Kettunen from OUSPG discovered that the combination of large numbers of columns and column groups in a table could cause the array containing the columns during rendering to overwrite itself. This can lead to a user-after-free causing 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