A cross-origin restriction bypass flaw was found in Firefox:
Security researcher Abdulrahman Alqabandi reported that the fetch() API did not correctly implement the Cross-Origin Resource Sharing (CORS) specification, allowing a malicious page to access private data from other origins. Mozilla developer Ben Kelly independently reported the same issue.
This issue was fixed in Firefox 41.0.2.
Fixed in Fedora in packages:
This issue did not affect the versions of firefox as shipped with Red Hat Enterprise Linux 5, 6, and 7.