system
Describe <CVE-2019-9721>.
user
What is <CVE-2019-9721>?
assistant
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..