Security readout for executives and security teams
Plain-English summary
SWFTools through 20200710 has a memory corruption flaw that can allow code execution when vulnerable tooling processes malicious input. The main business risk is in automated file conversion or parsing workflows that accept external SWF-related content.
Executive priority
Treat as high priority where SWFTools handles outside files, especially in production conversion pipelines. Priority is lower for environments without SWFTools or without untrusted input paths.
Technical view
CVE-2021-39595 is a stack-buffer-overflow in rfx_alloc() in mem.c in SWFTools through 20200710. The CVE states it can allow code execution. The provided sources do not include CVSS, CWE, CPEs, exploit details, or a confirmed fixed version.
Likely exposure
Exposure is most likely on servers, build systems, or analyst workstations running SWFTools through 20200710 and processing untrusted or externally supplied files. Evidence is insufficient to name specific packaged distributions or downstream products.
Exploitation context
CISA KEV status is false in the provided bundle, and no cited source confirms active exploitation. Practical risk depends on whether an attacker can cause vulnerable SWFTools components to parse a crafted file.
Researcher notes
The public record is sparse. It identifies rfx_alloc() in mem.c and claims code execution, but does not provide scoring, affected CPEs, exploit maturity, or a fixed release. Avoid assuming more than the sources state.
Mitigation direction
- Inventory SWFTools installations and confirm version or source revision.
- Stop processing untrusted SWF-related files with vulnerable SWFTools until remediated.
- Check upstream or distribution guidance for an available patched build.
- Run necessary processing in a sandbox with least privilege.
- Restrict file upload and conversion workflows that invoke SWFTools.
Validation and detection
- Search servers, containers, and workstations for SWFTools binaries or packages.
- Confirm whether versions are through 20200710.
- Map workflows that pass external files into SWFTools.
- Review the cited GitHub issue and vendor packaging advisories for fixes.
- Check logs for unexpected SWFTools crashes during file processing.
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.
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.
Open ATT&CK lookupCVE-2021-39595 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/141CVE 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.