Security researcher window reported an issue where the protocol handler dialog appears, double click events are treated as two single click events. This was caused by the lack of a delay following the initial focus in the file download dialog. This could cause a second dialog to be sent the second click, leading to unintentional user initiated actions, such as the running of downloaded software from a maliciously positioned prompt. 


External Reference:

https://www.mozilla.org/security/announce/2016/mfsa2016-06.html


Acknowledgements:

Red Hat would like to thank the Mozilla project for reporting this issue. Upstream acknowledges window as the original reporter.

Statement:

This issue does not affect the version of firefox and thunderbird as shipped with Red Hat Enterprise Linux 5, 6 and 7.