mpv through 0.28.0 allows remote attackers to execute arbitrary code via a crafted web site, because it reads HTML documents containing VIDEO elements, and accepts arbitrary URLs in a src attribute without a protocol whitelist in player/lua/ytdl_hook.lua. For example, an av://lavfi:ladspa=file= URL signifies that the product should call dlopen on a shared object file located at an arbitrary local pathname. The issue exists because the product does not consider that youtube-dl can provide a potentially unsafe URL.
https://www.debian.org/security/2018/dsa-4105
https://security.gentoo.org/glsa/201805-05
https://github.com/mpv-player/mpv/issues/5456
https://github.com/mpv-player/mpv/commit/e6e6b0dcc7e9b0dbf35154a179b3dc1fcfcaff43