Mozilla Foundation Security Advisory 2013-70
Title: Bypass of XrayWrappers using XBL
Announced: August 6, 2013
Reporter: Bobby Holley, moz_bug_r_a4
Products: Firefox, Seamonkey
Fixed in: Firefox 23.0
Mozilla Developer Bobby Holley and Mozilla security researcher moz_bug_r_a4 discovered a mechanism where XBL scopes can be be used to circumvent XrayWrappers from within the Chrome on unprivileged objects. This allows web content to potentially confuse privileged code and weaken invariants and can lead to cross-site scripting (XSS) attacks.
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.