The flashsv_decode_frame function in libavcodec/flashsv.c in FFmpeg before 2.1 does not properly validate a certain height value, which allows remote attackers to cause a denial of service (out-of-bounds array access) or possibly have unspecified other impact via crafted Flash Screen Video data.
https://security.gentoo.org/glsa/201603-06
http://www.debian.org/security/2014/dsa-2855
http://openwall.com/lists/oss-security/2013/12/08/3