CVE-2021-28856Public exploit

Process crash via zero PICT pixel size

Published Apr 14, 2021 · Updated Jan 26, 2026

Divide-by-zero in Deark before 1.5.8 allows context-dependent attackers to crash the process via a crafted PICT file. The PICT pixmap parser's fmtutil_macbitmap_read_pixmap_only_fields function divides rowbytes times eight by an unchecked pixelsize that can be zero. The file must be opened or processed by Deark, and successful exploitation terminates that Deark process without reading or modifying data.

CVSS severity5.5
Medium
EPSS probability0.84%
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 Deark before 1.5.8 allows context-dependent attackers to crash the process via a crafted PICT file. The PICT pixmap parser's fmtutil_macbitmap_read_pixmap_only_fields function divides rowbytes times eight by an unchecked pixelsize that can be zero. The file must be opened or processed by Deark, and successful exploitation terminates that Deark process without reading or modifying data.

The record

CVE
CVE-2021-28856
Published
Apr 14, 2021
Updated
Jan 26, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-369, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 14, 2021CVE publishedPublication date reported by the CVE source.
  2. Jan 26, 2026Record 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
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.

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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 exploitPublished

Weakness, pattern, technique

CWE-369Divide By Zero
T1204.002Malicious File

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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