CVE-2021-39849

Application crash via undisclosed null pointer dereference

Published Sep 29, 2021 · Updated Sep 16, 2024

Null pointer dereference in Adobe Acrobat Reader allows attackers to crash affected July 2021 and earlier releases with a malicious file. Adobe identifies the weakness but has not disclosed the affected parser, function, or invalid pointer operation. Exploitation requires a victim to open the file and is limited to interrupting the Reader process in the current user's context.

CVSS severity5.5
Medium
EPSS probability1.94%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Null pointer dereference in Adobe Acrobat Reader allows attackers to crash affected July 2021 and earlier releases with a malicious file. Adobe identifies the weakness but has not disclosed the affected parser, function, or invalid pointer operation. Exploitation requires a victim to open the file and is limited to interrupting the Reader process in the current user's context.

The record

CVE
CVE-2021-39849
Published
Sep 29, 2021
Updated
Sep 16, 2024
Vendor
Adobe
Product
Adobe Acrobat Reader
Classifications
CWE-476, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 29, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 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 <=17.0-Classic 2021 July
  2. Affected versionversion=unspecified <=20.0-Classic 2021 July
  3. Affected versionversion=unspecified <=DC 2021 July
  4. Affected versionversion=unspecified <=None

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Adobe · Adobe Acrobat Readerversion=unspecified <=17.0-Classic 2021 July; version=unspecified <=20.0-Classic 2021 July; version=unspecified <=DC 2021 July; version=unspecified <=None

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P
5.5Adobe Systems IncorporatedCVSS: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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1204.002User Execution: Malicious File

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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