CVE-2020-21679Public exploit

Conversion crash via out-of-bounds heap write

Published Aug 22, 2023 · Updated Oct 7, 2024

Heap buffer overflow in GraphicsMagick 1.4 allows attackers to crash image conversion by supplying a crafted image for PCX output. In coders/pcx.c, WritePCXImage writes a byte immediately past an allocated heap buffer while encoding crafted input as PCX. A user or automated workflow must pass the crafted image to the converter; successful exploitation aborts the conversion process.

CVSS severity5.5
Medium
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap buffer overflow in GraphicsMagick 1.4 allows attackers to crash image conversion by supplying a crafted image for PCX output. In coders/pcx.c, WritePCXImage writes a byte immediately past an allocated heap buffer while encoding crafted input as PCX. A user or automated workflow must pass the crafted image to the converter; successful exploitation aborts the conversion process.

The record

CVE
CVE-2020-21679
Published
Aug 22, 2023
Updated
Oct 7, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1499
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 22, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 7, 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 vectorlocal
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1499Endpoint Denial of Service

Public exploit references

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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