Using the Address Sanitizer tool, security researcher Atte Kettunen from OUSPG discovered a use-after-free in Web Audio due to an issue with how control messages for Web Audio are ordered and processed. This leads to a potentially exploitable crash.
In general this flaw cannot be exploited through email in the Thunderbird product because scripting is disabled, but is potentially a risk in browser or browser-like contexts.
Red Hat would like to thank the Mozilla project for reporting this issue. Upstream acknowledges Atte Kettunen as the original reporter.
This issue does not affect the version of thunderbird as shipped with Red Hat Enterprise Linux 5 and 6, or the version of firefox as shipped with Red Hat Enterprise Linux 5, 6, and 7.