Mozilla Firefox before 48.0 does not properly set the LINKABLE and URI_SAFE_FOR_UNTRUSTED_CONTENT flags of about: URLs that are used for error pages, which makes it easier for remote attackers to conduct spoofing attacks via a crafted URL, as demonstrated by misleading text after an about:neterror?d= substring.
https://security.gentoo.org/glsa/201701-15
https://bugzilla.mozilla.org/show_bug.cgi?id=1253673
http://www.ubuntu.com/usn/USN-3044-1
http://www.securitytracker.com/id/1036508
http://www.securityfocus.com/bid/92260
http://www.mozilla.org/security/announce/2016/mfsa2016-83.html
http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00029.html
http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00004.html