A denial of service in the subtitle decoder in FFmpeg 3.2 and 4.1 allows attackers to hog the CPU via a crafted video file in Matroska format, because handle_open_brace in libavcodec/htmlsubtitles.c has a complex format argument to sscanf.
Source: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-9721
Reference (s):
- BID:107384
- URL: http://www.securityfocus.com/bid/107384
- https://git.ffmpeg.org/gitweb/ffmpeg.git/commit/894995c41e0795c7a44f81adc4838dedc3932e65
- https://github.com/FFmpeg/FFmpeg/commit/273f2755ce8635d42da3cde0eeba15b2e7842774
- UBUNTU:USN-3967-1