What is CVE-2021-20309?

CVE-2021-20309 is a high-severity vulnerability in Imagemagick, classified under Divide By Zero. CVSS score: 7.5/10. Published 2021-05-11.

How severe is CVE-2021-20309?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Imagemagick

CVE-2021-20309

A flaw was found in ImageMagick in versions before 7.0.11 and before 6.9.12, where a division by zero in WaveImage() of MagickCore/visual-effects.c may trigger undefined behavior via a crafted image file submitted to an application using ImageMagick. The highest threat from this vulnerability is to system availability.

Published 2021-05-11 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.023 (82.7th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 83rd percentile — 82.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.023 · newest: 0.023 · change: 0.000

Affected products

Imagemagick
Debian Linux — versions 9.0
Imagemmagick — versions ImageMagick 7.0.11, ImageMagick 6.9.12

Weakness classification (CWE)

CWE-369 — Divide By Zero

References

bugzilla.redhat.com/show_bug.cgi (Patch, Third Party Advisory, Issue Tracking)
lists.debian.org/debian-lts-announce/2021/06/msg00000.html (mailing-list, Mailing List, Third Party Advisory)
lists.debian.org/debian-lts-announce/2023/05/msg00020.html (mailing-list)

Frequently asked questions

What is CVE-2021-20309?: CVE-2021-20309 is a high-severity vulnerability in Imagemagick, classified under Divide By Zero. CVSS score: 7.5/10. Published 2021-05-11.
How severe is CVE-2021-20309?: High severity. CVSS v3 base score is 7.5 out of 10.