CVE-2021-20176

Service interruption via zero Poisson-noise attenuation

Published Feb 5, 2021 · Updated Aug 3, 2024

Divide-by-zero in gem.c in ImageMagick 6.9.11-57 and 7.0.10-57 allows attackers to interrupt image-processing applications. GenerateDifferentialNoise derives SigmaPoisson from attenuation, then divides QuantumRange multiplied by the iteration count by SigmaPoisson without rejecting zero. Only a workflow that processes a crafted file with zero attenuation reaches the fault; reported impact is limited to application availability.

CVSS severity5.5
Medium
EPSS probability0.92%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Divide-by-zero in gem.c in ImageMagick 6.9.11-57 and 7.0.10-57 allows attackers to interrupt image-processing applications. GenerateDifferentialNoise derives SigmaPoisson from attenuation, then divides QuantumRange multiplied by the iteration count by SigmaPoisson without rejecting zero. Only a workflow that processes a crafted file with zero attenuation reaches the fault; reported impact is limited to application availability.

The record

CVE
CVE-2021-20176
Published
Feb 5, 2021
Updated
Aug 3, 2024
Vendor
ImageMagick Studio LLC
Product
ImageMagick
Classifications
CWE-369, T1499.004
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 5, 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

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Is a vulnerable build present?

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

  1. Affected versionversion=6.9.11-57, 7.0.10-57

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

ImageMagick Studio LLC · ImageMagickversion=6.9.11-57, 7.0.10-57

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P

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)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-369Divide By Zero
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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