The Internal feed reader APIs that crossed the sandbox barrier allowed for a sandbox escape and escalation of privilege if combined with another vulnerability that resulted in remote code execution inside the sandboxed process.
Name: the Mozilla project
Upstream: Paul Theriault
This issue has been addressed in the following products:
Red Hat Enterprise Linux 7
Via RHSA-2017:1106 https://access.redhat.com/errata/RHSA-2017:1106