What is CVE-2020-20891?

CVE-2020-20891 is a high-severity vulnerability in Ffmpeg, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 8.8/10. Published 2021-09-20.

How severe is CVE-2020-20891?

High severity. CVSS v3 base score is 8.8 out of 10.

Is CVE-2020-20891 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Buffer overflow in Ffmpeg

CVE-2020-20891

Buffer Overflow vulnerability in function config_input in libavfilter/vf_gblur.c in Ffmpeg 4.2.1, allows attackers to cause a Denial of Service or other unspecified impacts.

Vulnerability class: Buffer Overflow

Published 2021-09-20 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.012 (67.8th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 68th percentile — 67.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.012 · newest: 0.012 · change: 0.000

Affected products

Ffmpeg — versions 4.2.1

Weakness classification (CWE)

CWE-120 — Buffer Copy without Checking Size of Input (Classic Buffer Overflow)

Public proof-of-concept exploits

akaganeite/CVE4PP

References

trac.ffmpeg.org/ticket/8282 (Exploit, Issue Tracking, Vendor Advisory)
git.ffmpeg.org/gitweb/ffmpeg.git/commit/64a805883d7223c868a683f0030837d859edd2ab (Mailing List, Vendor Advisory)

Frequently asked questions

What is CVE-2020-20891?: CVE-2020-20891 is a high-severity vulnerability in Ffmpeg, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 8.8/10. Published 2021-09-20.
How severe is CVE-2020-20891?: High severity. CVSS v3 base score is 8.8 out of 10.
Is CVE-2020-20891 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.