CVE-2021-40726

Code execution via AcroForm listbox use-after-free

Published Oct 7, 2021 · Updated Sep 17, 2024

Use-after-free in Adobe Acrobat Reader 2021.005.20060 and earlier allows attackers to execute code through a crafted AcroForm listbox. Adobe identifies AcroForm listbox processing as the affected locus but has not disclosed the responsible function or object-lifetime sequence. Opening a malicious file or visiting a malicious page is required; successful exploitation runs code in the current user's context on affected Windows or macOS installations.

CVSS severity7.8
High
EPSS probability5.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Adobe Acrobat Reader 2021.005.20060 and earlier allows attackers to execute code through a crafted AcroForm listbox. Adobe identifies AcroForm listbox processing as the affected locus but has not disclosed the responsible function or object-lifetime sequence. Opening a malicious file or visiting a malicious page is required; successful exploitation runs code in the current user's context on affected Windows or macOS installations.

The record

CVE
CVE-2021-40726
Published
Oct 7, 2021
Updated
Sep 17, 2024
Vendor
Adobe
Product
Adobe Acrobat Reader
Classifications
CWE-416, T1203
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 7, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 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=unspecified <=2017.011.30199
  2. Affected versionversion=unspecified <=2020.004.30006
  3. Affected versionversion=unspecified <=2021.005.20060
  4. Affected versionversion=unspecified <=None

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Adobe · Adobe Acrobat Readerversion=unspecified <=2017.011.30199; version=unspecified <=2020.004.30006; version=unspecified <=2021.005.20060; version=unspecified <=None

Published CVSS scores

7.8AdobeCVSS:3.0/AV:L/AC:L/PR:N/UI:R/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)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1203Exploitation for Client Execution

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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