Security researcher Masato Kinugawa reported a cross-origin information leak through the error events in web workers. This violates same-origin policy and the leaked information could potentially be used by a malicious party to gather authentication tokens and other data from third-party websites.

This issue affects other browsers as well and is not limited to Mozilla products.


External Reference:

https://www.mozilla.org/security/announce/2015/mfsa2015-140.html


Acknowledgements:

Red Hat would like to thank the Mozilla project for reporting this issue. Upstream acknowledges Masato Kinugawa  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.