Provide references for CVE-2017-1000421.
Where can I find more information about CVE-2017-1000421?
References are available at: https://lists.debian.org/debian-lts-announce/2018/01/msg00006.html, https://www.debian.org/security/2018/dsa-4084, https://github.com/kohler/gifsicle/issues/114.