CVE-2021-39543

Denial of service via null pointer dereference

Published Sep 20, 2021 · Updated Aug 4, 2024

A NULL pointer dereference in pdftools through 20200714 allows attackers to cause a denial of service via a crafted PDF input. Analyze::AnalyzeRoot in analyze.cpp dereferences a NULL object while analyzing malformed document structure, causing the process to crash. Exploitation requires local execution of pdftools and user interaction to process attacker-controlled input; the reported consequence is service interruption without data disclosure or modification.

CVSS severity5.5
Medium
EPSS probability0.64%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A NULL pointer dereference in pdftools through 20200714 allows attackers to cause a denial of service via a crafted PDF input. Analyze::AnalyzeRoot in analyze.cpp dereferences a NULL object while analyzing malformed document structure, causing the process to crash. Exploitation requires local execution of pdftools and user interaction to process attacker-controlled input; the reported consequence is service interruption without data disclosure or modification.

The record

CVE
CVE-2021-39543
Published
Sep 20, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-476, T1203
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 20, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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?

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

5.5NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
4.3NVDAV: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 exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
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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