CVE-2021-21939Public exploitNetwork attack vector

Code execution via unchecked XWD row copy

Published Apr 14, 2022 · Updated Apr 15, 2025

Heap-based buffer overflow in Accusoft ImageGear 19.10 allows attackers to execute code by supplying a crafted XWD image. In xwdread_read_bitmap, BytesPerLine from the file controls OS_memcpy, but the destination is sized from PixmapDepth and PixmapWidth without comparing those values. Any host application that passes attacker-controlled XWD content to the library can overwrite heap memory and execute code in that application's security context.

CVSS severity9.8
Critical
EPSS probability1.59%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in Accusoft ImageGear 19.10 allows attackers to execute code by supplying a crafted XWD image. In xwdread_read_bitmap, BytesPerLine from the file controls OS_memcpy, but the destination is sized from PixmapDepth and PixmapWidth without comparing those values. Any host application that passes attacker-controlled XWD content to the library can overwrite heap memory and execute code in that application's security context.

The record

CVE
CVE-2021-21939
Published
Apr 14, 2022
Updated
Apr 15, 2025
Vendor
Accusoft
Product
ImageGear
Classifications
CWE-787, CWE-120, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 14, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 15, 2025Record 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=19.10

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Accusoft · ImageGearversion=19.10

Published CVSS scores

9.8Cisco TalosCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1203Exploitation for Client Execution

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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