CVE-2021-39587: n/a vulnerability

Security readout for executives and security teams

Plain-English summary

This CVE describes a crash flaw in swftools through 20200710. A crafted or malformed SWF file could trigger a NULL pointer dereference and stop the tool, causing denial of service for workflows that process SWF content.

Executive priority

Prioritize where swftools processes untrusted SWF files in automated business workflows. Without active exploitation or CVSS evidence, this is a hygiene and resilience issue, not a confirmed emergency.

Technical view

The reported flaw is a NULL pointer dereference in swf_DumpABC() in abc.c. The CVE states it can cause denial of service. The provided sources do not include CVSS, CWE, exploitability details, or confirmed fixed versions.

Likely exposure

Exposure is likely limited to environments that still run swftools through 20200710 and process SWF files, especially files supplied by users, partners, archives, or automated ingestion pipelines.

Exploitation context

The source bundle does not show CISA KEV listing or active exploitation evidence. The practical impact described is denial of service, not code execution or data theft.

Researcher notes

Evidence is sparse. The CVE identifies swftools through 20200710 and a NULL pointer dereference in swf_DumpABC(), but the provided record lacks affected CPEs, CVSS, CWE mapping, and remediation confirmation.

Mitigation direction

Inventory systems and jobs that use swftools.
Avoid processing untrusted SWF files with affected swftools versions.
Run SWF processing in isolated, resource-limited workers.
Check project issue and release history for vendor guidance or fixes.
Replace swftools if unsupported in production workflows.

Validation and detection

Confirm deployed swftools version or commit date.
Identify whether SWF input is user-controlled or external.
Review crash logs around SWF or ABC processing.
Confirm whether swf_DumpABC-related workflows are enabled.
Document compensating isolation and input-handling controls.

Prepared: Jun 2, 2026, 18:22 UTC (UTC+00:00)
Confidence: medium
Sources: 3

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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Vulnerability profileCVE Program record

Severity: Unknown
CVSS: Not scored
Known Exploited: No
Published: Sep 20, 2021, 15:27 UTC (UTC+00:00)

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors

0Timeline events

0ADP providers

2Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

CVE List V5 sourceCVE List V5
https://github.com/matthiaskramm/swftools/issues/129CVE reference · x_refsource_MISC

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus

n/an/an/aListed

Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CVE-2021-39587: An issue was discovered in swftools through 20200710.