CVE-2021-20309Network attack vector

Service interruption via unchecked wave length

Published May 11, 2021 · Updated Aug 3, 2024

Divide-by-zero in ImageMagick before 7.0.11 and before 6.9.12 allows remote attackers to crash image-processing applications. The WaveImage() loop divides its phase calculation by an unchecked, attacker-controlled wave_length value when processing a crafted image. Any application that accepts untrusted images and invokes the wave effect can terminate or exhibit other undefined behavior, interrupting that application's service.

CVSS severity7.5
High
EPSS probability2.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Divide-by-zero in ImageMagick before 7.0.11 and before 6.9.12 allows remote attackers to crash image-processing applications. The WaveImage() loop divides its phase calculation by an unchecked, attacker-controlled wave_length value when processing a crafted image. Any application that accepts untrusted images and invokes the wave effect can terminate or exhibit other undefined behavior, interrupting that application's service.

The record

CVE
CVE-2021-20309
Published
May 11, 2021
Updated
Aug 3, 2024
Vendor
ImageMagick Studio LLC
Product
ImageMagick
Classifications
CWE-369, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 11, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=ImageMagick 7.0.11, ImageMagick 6.9.12

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ImageMagick Studio LLC · ImageMagickversion=ImageMagick 7.0.11, ImageMagick 6.9.12

Published CVSS scores

7.8NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:C
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-369Divide By Zero
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo