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Fencer Intel
high 7.5

CVE-2020-21041 json

Buffer Overflow vulnerability exists in FFmpeg 4.1 via `apng_do_inverse_blend` in...

published 5y ago modified 3mo ago also EUVD-2020-13820 , JLSEC-2025-113

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.1%
EPSS 2.1% chance of exploitation in 30 days, percentile 81%
public exploits
0
none known

Summary

Buffer Overflow vulnerability exists in FFmpeg 4.1 via apng_do_inverse_blend in libavcodec/pngenc.c, which could let a remote malicious user cause a Denial of Service

Patch / fix

  • julia FFMPEG_jll 4.3.1+0
  • ffmpeg Debian 14, Debian 13, Debian 12 7:4.3.2-0+deb11u2

debian advisories DEBIAN-CVE-2020-21041

  • 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+esm1

ubuntu advisories UBUNTU-CVE-2020-21041

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 +10 more 3.4.2-4.34.2
  • ffmpeg SLE Workstation Extension 15 SP3, SLE Workstation Extension 15 SP2, SLE Module for Package Hub 15 SP3 +3 more 3.4.2-11.3.1

suse advisories SUSE-SU-2021:2929-1SUSE-SU-2021:2322-1

  • ffmpeg openSUSE Leap 15.3 3.4.2-11.3.1

opensuse advisories openSUSE-SU-2021:2322-1

  • 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-2020-21041

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

Is CVE-2020-21041 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Exploit prediction

2.07% chance of exploitation in the next 30 days, higher than 81% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • trac.ffmpeg.org https://trac.ffmpeg.org/ticket/7989 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
julia FFMPEG_jll
<4.3.1+0
4.3.1+0

Classification

Weakness
  • CWE-120 Buffer Copy without Checking Size of Input

References

Sources

Fencer Intel 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.