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Fencer Vulns
critical 9.8

CVE-2021-38171 json

`adts_decode_extradata` in `libavformat/adtsenc.c` in FFmpeg 4.4 does not check the `init_get_bits`...

published 2021-08-21 5 y ago modified 2026-07-23 3 mo ago also EUVD-2021-24641 , JLSEC-2025-118

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.4%
EPSS 2.4% chance of exploitation in 30 days, percentile 84%
public exploits
0
none known

Summary

adts_decode_extradata in libavformat/adtsenc.c in FFmpeg 4.4 does not check the init_get_bits return value, which is a necessary step because the second argument to init_get_bits can be crafted.

Patch / fix

  • julia FFMPEG_jll 4.4.2+0
  • ffmpeg Debian 14, Debian 13, Debian 12 7:4.4.1-1

debian advisories DEBIAN-CVE-2021-38171

  • ffmpeg Ubuntu 18.04 LTS 7:3.4.11-0ubuntu0.1
  • ffmpeg Ubuntu 20.04 LTS 7:4.2.7-0ubuntu0.1
  • ffmpeg Ubuntu Pro 16.04 LTS 7:2.8.17-0ubuntu0.1+esm4

ubuntu advisories UBUNTU-CVE-2021-38171

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • ffmpeg SLES for SAP 15 SP1, SLES for SAP 15, SLES 15-LTSS +7 more 3.4.2-4.37.1
  • ffmpeg SLE Workstation Extension 15 SP3, SLE Workstation Extension 15 SP2, SLE Module for Package Hub 15 SP3 +3 more 3.4.2-11.11.1

suse advisories SUSE-SU-2021:3212-1SUSE-SU-2021:3193-1

  • ffmpeg-4 openSUSE Tumbleweed 4.4-5.2
  • ffmpeg openSUSE Leap 15.3 3.4.2-11.11.1

opensuse advisories openSUSE-SU-2024:10754-1openSUSE-SU-2021:3193-1

  • ffmpeg Alpine 3.13 4.3.3-r0
  • ffmpeg Alpine 3.24, Alpine 3.23, Alpine 3.22 +8 more 4.4.1-r0
  • ffmpeg4 Alpine 3.22, Alpine 3.21, Alpine 3.20 +4 more 4.4.1-r0

alpine advisories ALPINE-CVE-2021-38171

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • ffmpeg Arch Linux 2:4.4.1-1

arch linux advisories AVG-1989

Exploit prediction

2.41% chance of exploitation in the next 30 days, higher than 84% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P
OSV 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
julia FFMPEG_jll
>=4.4.0+0, <4.4.2+0
4.4.2+0

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.