Security readout for executives and security teams
Plain-English summary
CVE-2021-39554 is a denial-of-service issue in SWFTools through 20200710. A specially crafted input can trigger a NULL pointer dereference in Lexer::Lexer(), crashing the process. The sources do not provide CVSS scoring, affected package metadata, or a named fix.
Executive priority
Treat as operational reliability risk, especially for services that automatically process uploaded or third-party content. Prioritize inventory and containment before urgent emergency response unless business-critical processing is exposed.
Technical view
The reported flaw is a NULL pointer dereference in Lexer::Lexer() in Lexer.cc in SWFTools through 20200710. The documented impact is application denial of service. The provided data does not describe code execution, privilege escalation, authentication impact, or confirmed remediation.
Likely exposure
Exposure is most likely where SWFTools processes untrusted or externally supplied content. The bundle lists affected versions only as SWFTools through 20200710 and does not provide package CPEs or platform details.
Exploitation context
The CVE record says an attacker can cause denial of service. CISA KEV status is false in the provided bundle, and no cited source establishes active exploitation.
Researcher notes
Evidence is sparse: no CVSS vector, CWE, CPE, patch reference, or exploit-in-the-wild confirmation is included. Analysis should remain limited to denial of service in SWFTools through 20200710.
Mitigation direction
- Inventory systems and workflows using SWFTools.
- Check whether deployed SWFTools versions are through 20200710.
- Restrict SWFTools processing of untrusted content where possible.
- Run SWFTools in constrained worker or sandboxed environments.
- Monitor the upstream issue and vendor guidance for fixes.
Validation and detection
- Confirm whether SWFTools is installed in production or build pipelines.
- Record exact SWFTools version and source of installation.
- Identify services that pass user-supplied content to SWFTools.
- Review crash logs for failures around Lexer.cc or parsing.
- Track the referenced GitHub issue for remediation status.
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-2021-39554 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/100CVE 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.