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CVE-2019-9721

A denial of service in the subtitle decoder in FFmpeg 3.2 and 4.1 allows attackers to hog the CPU...

6.5 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
Required

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

1.44%Up 0.1 points since Apr 14, 2021
90%50%10%1%

What each source reports

NVD Score used 6.5

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.

Record
CVE-2019-9721
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
CVSS 2.0
4.3 MediumAV:N/AC:M/Au:N/C:N/I:N/A:P
Weakness
CWE-125
Updated
2026-11-02
CVE List No score

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.

Record
CVE-2019-9721
Updated
2026-11-02
EUVDEUVD-2019-19086 No score

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.

Record
EUVD-2019-19086
Updated
2026-11-03
GitHub AdvisoriesGHSA-hjv9-2v6w-8wp3 6.5

A denial of service in the subtitle decoder in FFmpeg 3.2 and 4.1 allows attackers to hog the CPU...

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.

Record
GHSA-hjv9-2v6w-8wp3
CVSS 3.0
6.5 MediumCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Weakness
CWE-125
Updated
2026-11-02
OSVALPINE-CVE-2019-9721 6.5

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.

Record
ALPINE-CVE-2019-9721
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Updated
2026-11-03
OSV 6.5

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.

Record
CVE-2019-9721
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Updated
2026-11-07
Show 7 moreShow less
OSVDEBIAN-CVE-2019-9721 6.5

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.

Record
DEBIAN-CVE-2019-9721
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVJLSEC-2025-103 6.5

A denial of service in the subtitle decoder in FFmpeg 3.2 and 4.1 allows attackers to hog the CPU...

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.

Record
JLSEC-2025-103
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
CVSS 2.0
4.3 MediumAV:N/AC:M/Au:N/C:N/I:N/A:P
Updated
2026-11-02
OSVUBUNTU-CVE-2019-9721 6.5

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.

Record
UBUNTU-CVE-2019-9721
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
CVSS 3.0
6.5 MediumCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVopenSUSE-SU-2021:2919-1 No score

Security update for ffmpeg

This update for ffmpeg fixes the following issues:

  • CVE-2019-9721: Fix denial of service in the subtitle decoder in handle_open_brace from libavcodec/htmlsubtitles.c (bsc#1129714).
  • CVE-2020-22046: Fix a denial of service vulnerability exists in FFmpeg 4.2 due to a memory leak in the avpriv_float_dsp_allocl function in libavutil/float_dsp.c (bsc#1186849).
  • CVE-2020-22048: Fix a denial of service vulnerability exists in FFmpeg 4.2 due to a memory leak in the ff_frame_pool_get function in framepool.c (bsc#1186859).
  • CVE-2020-22049: Fix a denial of service vulnerability exists in FFmpeg 4.2 due to a memory leak in the wtvfile_open_sector function in wtvdec.c (bsc#1186861).
  • CVE-2020-22054: Fix a denial of service vulnerability exists in FFmpeg 4.2 due to a memory leak in the av_dict_set function in dict.c (bsc#1186863).
  • CVE-2020-21688: Fixed a heap-use-after-free in the av_freep function in libavutil/mem.c (bsc#1189348).
  • CVE-2020-21697: Fixed a heap-use-after-free in the mpeg_mux_write_packet function in libavformat/mpegenc.c (bsc#1189350).
  • CVE-2021-38114: Fixed a not checked return value of the init_vlc function (bsc#1189142).
Record
openSUSE-SU-2021:2919-1
Updated
2026-11-02
OSVSUSE-SU-2021:2919-1 No score

Security update for ffmpeg

This update for ffmpeg fixes the following issues:

  • CVE-2019-9721: Fix denial of service in the subtitle decoder in handle_open_brace from libavcodec/htmlsubtitles.c (bsc#1129714).
  • CVE-2020-22046: Fix a denial of service vulnerability exists in FFmpeg 4.2 due to a memory leak in the avpriv_float_dsp_allocl function in libavutil/float_dsp.c (bsc#1186849).
  • CVE-2020-22048: Fix a denial of service vulnerability exists in FFmpeg 4.2 due to a memory leak in the ff_frame_pool_get function in framepool.c (bsc#1186859).
  • CVE-2020-22049: Fix a denial of service vulnerability exists in FFmpeg 4.2 due to a memory leak in the wtvfile_open_sector function in wtvdec.c (bsc#1186861).
  • CVE-2020-22054: Fix a denial of service vulnerability exists in FFmpeg 4.2 due to a memory leak in the av_dict_set function in dict.c (bsc#1186863).
  • CVE-2020-21688: Fixed a heap-use-after-free in the av_freep function in libavutil/mem.c (bsc#1189348).
  • CVE-2020-21697: Fixed a heap-use-after-free in the mpeg_mux_write_packet function in libavformat/mpegenc.c (bsc#1189350).
  • CVE-2021-38114: Fixed a not checked return value of the init_vlc function (bsc#1189142).
Record
SUSE-SU-2021:2919-1
Updated
2026-11-02
OSVSUSE-SU-2021:2929-1 No score

Security update for ffmpeg

This update for ffmpeg fixes the following issues:

  • CVE-2019-9721: Fixed a denial of service in the subtitle decoder in handle_open_brace from libavcodec/htmlsubtitles.c (bsc#1129714).
  • CVE-2020-22046: Fixed a denial of service vulnerability due to a memory leak in the avpriv_float_dsp_allocl function in libavutil/float_dsp.c (bsc#1186849).
  • CVE-2020-22048: Fixed a denial of service vulnerability due to a memory leak in the ff_frame_pool_get function in framepool.c (bsc#1186859).
  • CVE-2020-22049: Fixed a denial of service vulnerability caused by a memory leak in the wtvfile_open_sector function in wtvdec.c (bsc#1186861).
  • CVE-2020-22054: Fixed a denial of service vulnerability due to a memory leak in the av_dict_set function in dict.c (bsc#1186863).
  • CVE-2020-13904: Fixed use-after-free via a crafted EXTINF duration in an m3u8 file (bsc#1172640).
  • CVE-2020-21041: Fixed buffer overflow vulnerability via apng_do_inverse_blend in libavcodec/pngenc.c (bsc#1186406).
  • CVE-2019-17539: Fixed NULL pointer dereference in avcodec_open2 in libavcodec/utils.c (bsc# 1154065).
  • CVE-2020-22026: Fixed buffer overflow vulnerability in config_input() at libavfilter/af_tremolo.c (bsc#1186583).
  • CVE-2020-22021: Fixed buffer overflow vulnerability in filter_edges function in libavfilter/vf_yadif.c (bsc#1186586).
  • CVE-2020-22020: Fixed buffer overflow vulnerability in build_diff_map() in libavfilter/vf_fieldmatch.c (bsc#1186587).
  • CVE-2020-22015: Fixed buffer overflow vulnerability in mov_write_video_tag() due to the out of bounds in libavformat/movenc.c (bsc#1186596).
  • CVE-2020-22016: Fixed a heap-based Buffer Overflow vulnerability at libavcodec/get_bits.h when writing .mov files (bsc#1186598).
  • CVE-2020-22017: Fixed a heap-based Buffer Overflow vulnerability in ff_fill_rectangle() in libavfilter/drawutils.c (bsc#1186600).
  • CVE-2020-22022: Fixed a heap-based Buffer Overflow vulnerability in filter_frame at libavfilter/vf_fieldorder.c (bsc#1186603).
  • CVE-2020-22023: Fixed a heap-based Buffer Overflow vulnerability in filter_frame at libavfilter/vf_bitplanenoise.c (bsc#1186604)
  • CVE-2020-22025: Fixed a heap-based Buffer Overflow vulnerability in gaussian_blur at libavfilter/vf_edgedetect.c (bsc#1186605).
  • CVE-2020-22031: Fixed a heap-based Buffer Overflow vulnerability at libavfilter/vf_w3fdif.c in filter16_complex_low() (bsc#1186613).
  • CVE-2020-22032: Fixed a heap-based Buffer Overflow vulnerability at libavfilter/vf_edgedetect.c in gaussian_blur() (bsc#1186614).
  • CVE-2020-22034: Fixed a heap-based Buffer Overflow vulnerability at libavfilter/vf_floodfill.c (bsc#1186616).
  • CVE-2020-20451: Fixed denial of service issue due to resource management errors via fftools/cmdutils.c (bsc#1186658).
  • CVE-2020-20448: Fixed divide by zero issue via libavcodec/ratecontrol.c (bsc#1186660).
  • CVE-2020-22038: Fixed denial of service vulnerability due to a memory leak in the ff_v4l2_m2m_create_context function in v4l2_m2m.c (bsc#1186757).
  • CVE-2020-22039: Fixed denial of service vulnerability due to a memory leak in the inavi_add_ientry function (bsc#1186758).
  • CVE-2020-22043: Fixed denial of service vulnerability due to a memory leak at the fifo_alloc_common function in libavutil/fifo.c (bsc#1186762).
  • CVE-2020-22044: Fixed denial of service vulnerability due to a memory leak in the url_open_dyn_buf_internal function in libavformat/aviobuf.c (bsc#1186763).
  • CVE-2020-22033,CVE-2020-22019: Fixed a heap-based Buffer Overflow Vulnerability at libavfilter/vf_vmafmotion.c in convolution_y_8bit() and in convolution_y_10bit() in libavfilter/vf_vmafmotion.c (bsc#1186615, bsc#1186597).
  • CVE-2020-21688: Fixed a heap-use-after-free in the av_freep function in libavutil/mem.c (bsc#1189348).
  • CVE-2020-21697: Fixed a heap-use-after-free in the mpeg_mux_write_packet function in libavformat/mpegenc.c (bsc#1189350).
  • CVE-2021-38114: Fixed a not checked return value of the init_vlc function (bsc#1189142).
Record
SUSE-SU-2021:2929-1
Updated
2026-11-02
OSVUSN-3967-1 No score

FFmpeg vulnerabilities

It was discovered that FFmpeg contained multiple security issues when handling certain multimedia files. If a user were tricked into opening a crafted multimedia file, an attacker could cause a denial of service via application crash.

Record
USN-3967-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
ffmpeg
Alpine:v3.10
 before 4.1.3-r0
4.1.3-r0
ffmpeg
Alpine:v3.11
 before 4.1.3-r0
4.1.3-r0
ffmpeg
Alpine:v3.12
 before 4.1.3-r0
4.1.3-r0
ffmpeg
Alpine:v3.13
 before 4.1.3-r0
4.1.3-r0
ffmpeg
Alpine:v3.14
 before 4.1.3-r0
4.1.3-r0
ffmpeg
Alpine:v3.15
 before 4.1.3-r0
4.1.3-r0
ffmpeg
Alpine:v3.16
 before 4.1.3-r0
4.1.3-r0
ffmpeg
Alpine:v3.17
 before 4.1.3-r0
4.1.3-r0
ffmpeg
Alpine:v3.18
 before 4.1.3-r0
4.1.3-r0
ffmpeg
Alpine:v3.19
 before 4.1.3-r0
4.1.3-r0
Show 40 moreShow less
Affected packages
PackageAffectedFixed
ffmpeg
Alpine:v3.20
 before 4.1.3-r0
4.1.3-r0
ffmpeg
Alpine:v3.21
 before 4.1.3-r0
4.1.3-r0
ffmpeg
Alpine:v3.22
 before 4.1.3-r0
4.1.3-r0
ffmpeg
Alpine:v3.23
 before 4.1.3-r0
4.1.3-r0
ffmpeg
Alpine:v3.24
 before 4.1.3-r0
4.1.3-r0
ffmpeg
Alpine:v3.8
 before 3.4.6-r0
3.4.6-r0
ffmpeg
Alpine:v3.9
 before 4.0.4-r0
4.0.4-r0
ffmpeg4
Alpine:v3.16
 before 4.1.3-r0
4.1.3-r0
ffmpeg4
Alpine:v3.17
 before 4.1.3-r0
4.1.3-r0
ffmpeg4
Alpine:v3.18
 before 4.1.3-r0
4.1.3-r0
ffmpeg4
Alpine:v3.19
 before 4.1.3-r0
4.1.3-r0
ffmpeg4
Alpine:v3.20
 before 4.1.3-r0
4.1.3-r0
ffmpeg4
Alpine:v3.21
 before 4.1.3-r0
4.1.3-r0
ffmpeg4
Alpine:v3.22
 before 4.1.3-r0
4.1.3-r0
ffmpeg
Debian:12
 before 7:4.1.3-1
7:4.1.3-1
ffmpeg
Debian:13
 before 7:4.1.3-1
7:4.1.3-1
ffmpeg
Debian:14
 before 7:4.1.3-1
7:4.1.3-1
FFMPEG_jll
Julia
 before 4.3.1+0
4.3.1+0
ffmpeg
SUSE:Linux Enterprise Module for Desktop Applications 15 SP2
From an advisory covering 8 CVEs
 before 3.4.2-11.8.2
3.4.2-11.8.2
ffmpeg
SUSE:Linux Enterprise Module for Desktop Applications 15 SP3
From an advisory covering 8 CVEs
 before 3.4.2-11.8.2
3.4.2-11.8.2
ffmpeg
SUSE:Linux Enterprise Module for Package Hub 15 SP2
From an advisory covering 8 CVEs
 before 3.4.2-11.8.2
3.4.2-11.8.2
ffmpeg
SUSE:Linux Enterprise Module for Package Hub 15 SP3
From an advisory covering 8 CVEs
 before 3.4.2-11.8.2
3.4.2-11.8.2
ffmpeg
SUSE:Linux Enterprise Workstation Extension 15 SP2
From an advisory covering 8 CVEs
 before 3.4.2-11.8.2
3.4.2-11.8.2
ffmpeg
SUSE:Linux Enterprise Workstation Extension 15 SP3
From an advisory covering 8 CVEs
 before 3.4.2-11.8.2
3.4.2-11.8.2
ffmpeg
SUSE:Linux Enterprise High Performance Computing 15-ESPOS
From an advisory covering 31 CVEs
 before 3.4.2-4.34.2
3.4.2-4.34.2
ffmpeg
SUSE:Linux Enterprise High Performance Computing 15-LTSS
From an advisory covering 31 CVEs
 before 3.4.2-4.34.2
3.4.2-4.34.2
ffmpeg
SUSE:Linux Enterprise High Performance Computing 15 SP1-ESPOS
From an advisory covering 31 CVEs
 before 3.4.2-4.34.2
3.4.2-4.34.2
ffmpeg
SUSE:Linux Enterprise High Performance Computing 15 SP1-LTSS
From an advisory covering 31 CVEs
 before 3.4.2-4.34.2
3.4.2-4.34.2
ffmpeg
SUSE:Linux Enterprise Server 15-LTSS
From an advisory covering 31 CVEs
 before 3.4.2-4.34.2
3.4.2-4.34.2
ffmpeg
SUSE:Linux Enterprise Server 15 SP1-BCL
From an advisory covering 31 CVEs
 before 3.4.2-4.34.2
3.4.2-4.34.2
ffmpeg
SUSE:Linux Enterprise Server 15 SP1-LTSS
From an advisory covering 31 CVEs
 before 3.4.2-4.34.2
3.4.2-4.34.2
ffmpeg
SUSE:Linux Enterprise Server for SAP Applications 15
From an advisory covering 31 CVEs
 before 3.4.2-4.34.2
3.4.2-4.34.2
ffmpeg
SUSE:Linux Enterprise Server for SAP Applications 15 SP1
From an advisory covering 31 CVEs
 before 3.4.2-4.34.2
3.4.2-4.34.2
ffmpeg
SUSE:Manager Proxy 4.0
From an advisory covering 31 CVEs
 before 3.4.2-4.34.2
3.4.2-4.34.2
ffmpeg
SUSE:Manager Retail Branch Server 4.0
From an advisory covering 31 CVEs
 before 3.4.2-4.34.2
3.4.2-4.34.2
ffmpeg
SUSE:Manager Server 4.0
From an advisory covering 31 CVEs
 before 3.4.2-4.34.2
3.4.2-4.34.2
ffmpeg
SUSE:Enterprise Storage 6
From an advisory covering 31 CVEs
 before 3.4.2-4.34.2
3.4.2-4.34.2
ffmpeg
Ubuntu:18.04:LTS
 before 7:3.4.6-0ubuntu0.18.04.1, plus listed versions
7:3.3.4-27:3.3.4-2build37:3.4-2ubuntu27:3.4-47:3.4-4build1
Show 6 moreShow less
7:3.4.1-17:3.4.1-1build17:3.4.2-17:3.4.2-1build17:3.4.2-27:3.4.4-0ubuntu0.18.04.1
7:3.4.6-0ubuntu0.18.04.1
ffmpeg
Ubuntu:18.04:LTS
From an advisory covering 4 CVEs
 before 7:3.4.6-0ubuntu0.18.04.1, plus listed versions
7:3.3.4-27:3.3.4-2build37:3.4-2ubuntu27:3.4-47:3.4-4build1
Show 6 moreShow less
7:3.4.1-17:3.4.1-1build17:3.4.2-17:3.4.2-1build17:3.4.2-27:3.4.4-0ubuntu0.18.04.1
7:3.4.6-0ubuntu0.18.04.1
ffmpeg
openSUSE:Leap 15.3
From an advisory covering 8 CVEs
 before 3.4.2-11.8.2
3.4.2-11.8.2

History

History
RecordedChangedSources
affected, facts
affected, aliases, referencesOSV
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2019-9721 is a medium vulnerability (CVSS 6.5) in Ffmpeg, published March 12, 2019. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.44%, the 73rd percentile. Fixed in ffmpeg 4.1.3-r0.

References

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