CVE-2021-39592Public exploit

Application crash via NULL pool entry dereference

Published Sep 20, 2021 · Updated Aug 4, 2024

NULL pointer dereference in SWFTools through 20200710 allows local users to crash swfdump by processing a crafted SWF file. While reading ActionScript 3 bytecode, swfdump reaches pool_lookup_uint through constant_fromindex and dereferences address zero at pool.c line 1024. Exploitation requires a user to run swfdump on the crafted file; the demonstrated consequence is process termination, without reported data disclosure or modification.

CVSS severity5.5
Medium
EPSS probability0.66%
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 SWFTools through 20200710 allows local users to crash swfdump by processing a crafted SWF file. While reading ActionScript 3 bytecode, swfdump reaches pool_lookup_uint through constant_fromindex and dereferences address zero at pool.c line 1024. Exploitation requires a user to run swfdump on the crafted file; the demonstrated consequence is process termination, without reported data disclosure or modification.

The record

CVE
CVE-2021-39592
Published
Sep 20, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-476, T1204.002
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

4.3NVDAV:N/AC:M/Au:N/C:N/I:N/A:P
5.5UbuntuCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
5.5NVDCVSS: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 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 exploitPublished

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1204.002Malicious File

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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