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Fencer Vulns
high 8.8

CVE-2021-30123 json

FFmpeg <=4.3 contains a buffer overflow vulnerability in libavcodec through a crafted file that may...

published 2021-04-07 5 y ago modified 2026-07-23 3 mo ago also EUVD-2021-17063 , JLSEC-2025-112

cvss
8.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.4%
EPSS 3.4% chance of exploitation in 30 days, percentile 89%
public exploits
0
none known

Summary

FFmpeg <=4.3 contains a buffer overflow vulnerability in libavcodec through a crafted file that may lead to remote code execution.

Patch / fix

  • julia FFMPEG_jll 4.4.2+0
  • ffmpeg Alpine 3.24, Alpine 3.23, Alpine 3.22 +8 more 4.4-r0
  • ffmpeg4 Alpine 3.22, Alpine 3.21, Alpine 3.20 +4 more 4.4-r0

alpine advisories ALPINE-CVE-2021-30123

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

Exploit prediction

3.43% chance of exploitation in the next 30 days, higher than 89% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • trac.ffmpeg.org https://trac.ffmpeg.org/ticket/8845 referenced PoC, tagged "exploit" by a source, unverified
  • trac.ffmpeg.org https://trac.ffmpeg.org/ticket/8863 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD 2.0 6.8 AV:N/AC:M/Au:N/C:P/I:P/A:P
OSV 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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
  • CWE-120 Buffer Copy without Checking Size of Input

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.