CVE-2019-9721

Name: CVE-2019-9721
Creator: NVD / NIST
Published: 2019-03-12T09:29:00.577+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 1.42%

Last modified Jun 17, 2026

CVE-2019-9721 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. 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.. EPSS estimates a 1.42% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

EPSS Probability

1.42%

69.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-125

Affected Software

Vendor	Product	Versions
Ffmpeg	Ffmpeg	3.2
Ffmpeg	Ffmpeg	4.1
Canonical	Ubuntu Linux	18.04
Canonical	Ubuntu Linux	18.10
Canonical	Ubuntu Linux	19.04

References

http://www.securityfocus.com/bid/107384Broken Link
https://git.ffmpeg.org/gitweb/ffmpeg.git/commit/894995c41e0795c7a44f81adc4838dedc3932e65Mailing List, Patch, Third Party Advisory
https://github.com/FFmpeg/FFmpeg/commit/273f2755ce8635d42da3cde0eeba15b2e7842774Patch, Third Party Advisory
https://usn.ubuntu.com/3967-1/Third Party Advisory
http://www.securityfocus.com/bid/107384Broken Link
https://git.ffmpeg.org/gitweb/ffmpeg.git/commit/894995c41e0795c7a44f81adc4838dedc3932e65Mailing List, Patch, Third Party Advisory
https://github.com/FFmpeg/FFmpeg/commit/273f2755ce8635d42da3cde0eeba15b2e7842774Patch, Third Party Advisory
https://usn.ubuntu.com/3967-1/Third Party Advisory

Timeline

Published: Mar 12, 2019
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2019-9721?

How severe is CVE-2019-9721?

CVE-2019-9721 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 1.42% probability of exploitation in the next 30 days.

How do I fix CVE-2019-9721?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2019-9721?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST