The content security policy (CSP) "sandbox" directive did not create a unique origin for the document, causing it to behave as if the "allow-same-origin" keyword were always specified. This could allow a Cross-Site Scripting (XSS) attack to be launched from unsafe content. This vulnerability affects Firefox < 56, Firefox ESR < 52.4, and Thunderbird < 52.4.
https://www.mozilla.org/security/advisories/mfsa2017-23/
https://www.mozilla.org/security/advisories/mfsa2017-22/
https://www.mozilla.org/security/advisories/mfsa2017-21/
https://www.debian.org/security/2017/dsa-4014
https://www.debian.org/security/2017/dsa-3987
https://security.gentoo.org/glsa/201803-14
https://lists.debian.org/debian-lts-announce/2017/11/msg00000.html
https://bugzilla.mozilla.org/show_bug.cgi?id=1396320
https://access.redhat.com/errata/RHSA-2017:2885
https://access.redhat.com/errata/RHSA-2017:2831