Security readout for executives and security teams
Plain-English summary
CVE-2021-42199 is a heap buffer overflow in SWFTools through 20201222. If SWFTools processes a malicious SWF file, the flaw is reported to allow code execution. Business risk is highest where legacy SWF conversion or extraction is still automated.
Executive priority
Treat this as a focused legacy-media processing risk. Prioritize environments that ingest external SWF content or run SWFTools automatically, but do not assume internet-wide exposure or active exploitation from the provided evidence.
Technical view
The reported flaw is in swf_FontExtract_DefineTextCallback() in swftext.c. The CVE describes heap buffer overflow leading to code execution. The bundle provides no CVSS, CWE, confirmed fixed version, or named downstream affected products beyond SWFTools through 20201222.
Likely exposure
Exposure is most likely in systems, build pipelines, content-processing services, or analyst workstations that still run SWFTools on SWF files, especially files from users or third parties.
Exploitation context
CISA KEV is false, and the provided sources do not claim active exploitation. The practical risk depends on whether an attacker can get a crafted SWF processed by SWFTools.
Researcher notes
Evidence is limited to the CVE description and a GitHub issue reference. No CVSS vector, CWE mapping, exploit-in-the-wild claim, or patch identifier is included in the supplied bundle, so validation should start with installed usage and upstream issue review.
Mitigation direction
- Inventory systems and containers for SWFTools usage.
- Avoid processing untrusted SWF files with SWFTools where possible.
- Isolate SWFTools processing from sensitive systems and credentials.
- Check upstream issue and vendor guidance for fixed releases or workarounds.
- Remove SWFTools from workflows where it is no longer required.
Validation and detection
- Confirm whether SWFTools is installed or bundled in applications.
- Identify any workflows that process user-supplied or third-party SWF files.
- Check deployed SWFTools versions against through 20201222 exposure.
- Review the referenced GitHub issue for maintainer updates.
- Document compensating controls around SWF parsing services.
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-2021-42199 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/173CVE 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.