In Libav 12.3, a denial of service in the subtitle decoder allows attackers to hog the CPU via a crafted video file in Matroska format, because srt_to_ass in libavcodec/srtdec.c has a complex format argument to sscanf.Referenceshttps://github.com/libav/libav/blob/df744e3cf66548c9167ea857104a29d2ea92819e/libavcodec/srtdec.c#L90https://lgtm.com/security/
