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CVE Record

CVE-2021-39558: An issue was discovered in swftools through 20200710.

An issue was discovered in swftools through 20200710. A stack-buffer-overflow exists in the function VectorGraphicOutputDev::drawGeneralImage() located in VectorGraphicOutputDev.cc. 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

CVE-2021-39558 is a stack buffer overflow in swftools through 20200710. The CVE record says it can allow code execution, so risk is serious where swftools processes attacker-supplied files. Public source data does not name a CVSS score, fixed version, or confirmed exploitation.

Executive priority

Prioritize this if swftools is used in production file-processing paths, especially customer-upload or internet-facing workflows. If swftools is absent or only used on trusted internal files, urgency is lower, but inventory should still be completed.

Technical view

The issue is reported in VectorGraphicOutputDev::drawGeneralImage() in VectorGraphicOutputDev.cc. The described flaw is stack-based memory corruption, with potential code execution. The provided sources identify swftools through 20200710, but do not provide CPEs, CVSS metrics, patch details, or exploitation evidence.

Likely exposure

Exposure is most likely in systems that have swftools through 20200710 installed and use it to process untrusted or externally supplied content. The source bundle does not identify specific distributions, packaged products, or cloud services as affected.

Exploitation context

The CVE text states code execution is possible, but the provided sources do not show active exploitation. CISA KEV status is false in the bundle, so treat this as a serious memory-safety issue without confirmed exploitation evidence.

Researcher notes

Evidence is thin: the CVE description names the vulnerable function and code-execution impact, but lacks CVSS, CWE, CPEs, patch status, and exploit confirmation. Avoid assuming broader affected products without independent package or vendor evidence.

Mitigation direction

  • Inventory hosts, containers, and build images for swftools through 20200710.
  • Check the referenced project issue and vendor guidance for fixed release information.
  • Remove swftools where it is not operationally required.
  • Restrict swftools from processing untrusted files until guidance is confirmed.
  • Run file-processing workloads in isolated, least-privilege sandboxes.

Validation and detection

  • Confirm installed swftools versions across servers, containers, and CI images.
  • Identify workflows where swftools handles external or user-supplied files.
  • Review crash logs for unexplained swftools failures during image or document conversion.
  • Verify sandboxing, permissions, and network restrictions around conversion workers.
  • Track the GitHub issue and CVE record for remediation updates.
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

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

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-2021-39558 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.