Security readout for executives and security teams
Plain-English summary
CVE-2021-39594 is a denial-of-service flaw in swftools through 20200710. A crafted input can trigger a NULL pointer dereference in swftext.c, crashing the affected process. The business impact is availability disruption where swftools handles untrusted SWF content.
Executive priority
Treat as a targeted availability risk, not an emergency based on current evidence. Prioritize review if swftools processes untrusted files in production or customer-facing workflows.
Technical view
The reported bug is a NULL pointer dereference in updateusage() in swftext.c. Sources identify the impact as denial of service. The bundle does not provide CVSS, CWE, a confirmed patch version, affected package metadata, or detailed exploit conditions beyond swftools through 20200710.
Likely exposure
Exposure is most likely where swftools is installed in content-conversion, document-processing, malware-analysis, or legacy Flash workflows that parse external SWF files. The source bundle does not identify packaged distributions, default installations, or dependent products.
Exploitation context
The CVE is not listed as KEV in the provided bundle, and no cited source confirms active exploitation. Public evidence supports a crash/DoS condition, not code execution or privilege escalation.
Researcher notes
The record is sparse: no CVSS, CWE, patch reference, CPE, or exploit-status evidence is included. Analysis should remain constrained to DoS from NULL pointer dereference in swftools through 20200710 unless additional vendor data is obtained.
Mitigation direction
- Inventory systems and pipelines that install or invoke swftools.
- Avoid processing untrusted SWF files with affected swftools versions.
- Run SWF conversion jobs in isolated, resource-limited environments.
- Check the upstream GitHub issue and vendor packaging guidance for fixes.
- Remove swftools where legacy Flash processing is no longer required.
Validation and detection
- Check package inventories for swftools versions through 20200710.
- Identify automated workflows that pass external SWF files to swftools.
- Review crash logs for swftext or updateusage-related failures.
- Confirm whether vendor or distribution packages include a relevant fix.
- Document compensating controls for any retained affected installations.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
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
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2021-39594 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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.
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/142CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.