Certain response codes in FTP connections can result in the use of uninitialized values for ports in FTP operations. This vulnerability affects Firefox < 52, Firefox ESR < 45.8, Thunderbird < 52, and Thunderbird < 45.8.
https://www.debian.org/security/2017/dsa-3832
https://www.debian.org/security/2017/dsa-3805
https://security.gentoo.org/glsa/201705-07
https://security.gentoo.org/glsa/201705-06
http://www.securitytracker.com/id/1037966
http://www.securityfocus.com/bid/96693
http://rhn.redhat.com/errata/RHSA-2017-0498.html