Mozilla developer Olli Pettay reported that while investigating Mozilla Foundation Security Advisory 2015-28, he and Mozilla developer Boris Zbarsky alternate way to trigger a similar vulnerability. The previously reported flaw used an issue with SVG content navigation to bypass same-origin policy protections to run scripts in a privileged context. This newer variant found that the same flaw could be used during anchor navigation of a page, allowing bypassing of same-origin policy protections.

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.


External Reference:

http://www.mozilla.org/security/announce/2015/mfsa2015-40.html


Acknowledgements:

Red Hat would like to thank the Mozilla project for reporting this issue. Upstream acknowledges Olli Pettay and Boris Zbarsky as the original reporters.