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CVE Record

CVE-2021-39564: An issue was discovered in swftools through 20200710.

An issue was discovered in swftools through 20200710. A heap-buffer-overflow exists in the function swf_DumpActions() located in swfaction.c. It allows an attacker to cause code Execution.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

SWFTools through 20200710 has a heap buffer overflow in its SWF action dumping code. If the tool processes hostile or untrusted SWF content, the public CVE states this can lead to code execution. The available sources do not provide CVSS, CPEs, a fixed version, or exploitation evidence.

Executive priority

Prioritize environments where SWFTools handles files from customers, partners, email, uploads, or public sources. Business urgency is lower for offline, trusted-only use, but code execution potential makes exposed automated processing paths important to contain quickly.

Technical view

The issue is a heap-buffer-overflow in swf_DumpActions() in swfaction.c in SWFTools through 20200710. The CVE description says an attacker can cause code execution. Source metadata lacks CWE, CVSS, affected CPEs, and remediation details, so operational analysis should be bounded to confirmed SWFTools exposure.

Likely exposure

Exposure is most plausible where SWFTools through 20200710 is installed and processes external or attacker-controlled SWF files. Automated conversion, inspection, or content-processing workflows are the highest concern. Sources do not document deployment prevalence or downstream package impact.

Exploitation context

The provided bundle does not cite active exploitation. The KEV flag is false, and the sources do not establish exploit availability. Treat this as a potentially serious memory-safety issue because code execution is claimed, but do not assume in-the-wild exploitation from the available evidence.

Researcher notes

The evidence is thin: CVE text and a GitHub issue reference identify the vulnerable function and version range, but no CVSS, CWE, CPE, patch, or exploit status is supplied. Validate affected builds directly and avoid broad downstream claims not supported by the sources.

Mitigation direction

  • Inventory systems for SWFTools and confirm whether versions are through 20200710.
  • Stop processing untrusted SWF files with affected SWFTools builds where feasible.
  • Check upstream project guidance and linked issue for any fixed release or patch status.
  • Isolate SWFTools processing from privileged accounts and sensitive networks.
  • Restrict upload or ingestion paths that can feed SWF files to SWFTools.

Validation and detection

  • Search hosts, containers, and build images for installed SWFTools binaries or packages.
  • Confirm whether any workflow invokes SWFTools on external SWF content.
  • Review logs for SWFTools crashes while parsing SWF files.
  • Verify vendor or project remediation status before marking the issue resolved.
  • Document compensating controls if no fixed version is available.
Prepared
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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ATT&CK lookup starting points

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description · low confidence lookup

Execution behavior lookup

The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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CVE-2021-39564 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
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

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.