CVE-2021-21821Public exploitNetwork attack vector

Code execution via PDF font name overflow

Published Jul 8, 2021 · Updated Aug 3, 2024

Stack-based buffer overflow in Accusoft ImageGear 19.9 allows remote attackers to execute code via a crafted PDF file. The PDF process_fontname function copies attacker-controlled font-name data into a fixed-size stack buffer without adequate bounds checking, corrupting stack memory. Exploitation requires a host application to process the malicious PDF; successful corruption can execute code in that application's security context or crash it.

CVSS severity9.8
Critical
EPSS probability1.96%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in Accusoft ImageGear 19.9 allows remote attackers to execute code via a crafted PDF file. The PDF process_fontname function copies attacker-controlled font-name data into a fixed-size stack buffer without adequate bounds checking, corrupting stack memory. Exploitation requires a host application to process the malicious PDF; successful corruption can execute code in that application's security context or crash it.

The record

CVE
CVE-2021-21821
Published
Jul 8, 2021
Updated
Aug 3, 2024
Vendor
Accusoft
Product
ImageGear
Classifications
CWE-121, CWE-787, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 8, 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=Accusoft ImageGear 19.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Accusoft · ImageGearversion=Accusoft ImageGear 19.9

Published CVSS scores

9.8Cisco TalosCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 exploitPublished

Weakness, pattern, technique

CWE-121Stack-based Buffer Overflow
CWE-787Out-of-bounds Write
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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