CVE-2021-40211Network attack vector

Service crash via zero WMF inch value

Published Aug 22, 2023 · Updated Oct 3, 2024

Divide-by-zero in ImageMagick 7.1.0-4 allows attackers to crash image-processing applications via a crafted Windows metafile. ReadEnhMetaFile treats the attacker-controlled wInch field in a placeable WMF header as a divisor when calculating both metafile dimensions, without first rejecting zero. Processing the crafted file through a build with the Windows GDI EMF delegate triggers an arithmetic exception and interrupts the calling service.

CVSS severity7.5
High
EPSS probability0.95%
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 ImageMagick 7.1.0-4 allows attackers to crash image-processing applications via a crafted Windows metafile. ReadEnhMetaFile treats the attacker-controlled wInch field in a placeable WMF header as a divisor when calculating both metafile dimensions, without first rejecting zero. Processing the crafted file through a build with the Windows GDI EMF delegate triggers an arithmetic exception and interrupts the calling service.

The record

CVE
CVE-2021-40211
Published
Aug 22, 2023
Updated
Oct 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-369, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 22, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
6.5Amazon LinuxCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
7.5CanonicalCVSS: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

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Your stack

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