Security readout for executives and security teams
Plain-English summary
CVE-2021-39559 is a denial-of-service issue in swftools through 20200710. The reported flaw can crash the software through a NULL pointer dereference. Business urgency depends on whether swftools is used in automated workflows that process untrusted files.
Executive priority
Treat this as a targeted availability risk, not a confirmed critical compromise risk. Prioritize review if swftools supports customer-facing or automated file-processing services.
Technical view
The CVE identifies a NULL pointer dereference in GString::~GString() in GString.cc in swftools through 20200710. The documented impact is denial of service. The source bundle does not provide CVSS, CWE, affected CPEs, patch details, or confirmed exploit status.
Likely exposure
Exposure is most likely where swftools through 20200710 is installed and used to process files from users, partners, email, web uploads, or other untrusted sources.
Exploitation context
The provided sources do not show CISA KEV listing or active exploitation. They describe attacker-caused denial of service, but do not provide enough evidence to state exploit maturity or real-world use.
Researcher notes
Evidence is sparse. The CVE record names the vulnerable destructor and denial-of-service impact, but lacks CVSS, CWE, CPEs, and remediation data. Avoid assuming code execution, broad product impact, or active exploitation.
Mitigation direction
- Inventory systems and containers for swftools through 20200710.
- Check the upstream project issue and vendor guidance for fixed versions or patches.
- Avoid processing untrusted files with affected swftools builds.
- Run file-processing jobs with sandboxing, resource limits, and crash isolation.
- Monitor conversion or processing services for repeated crashes.
Validation and detection
- Confirm installed swftools versions on servers, build images, and developer workstations.
- Identify workflows where swftools processes external or user-supplied files.
- Review crash logs for NULL dereference patterns involving GString.cc or GString::~GString().
- Verify whether upstream guidance names a patched release before upgrading.
- Confirm production pipelines isolate swftools failures from core 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.
CVE-2021-39559 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/101CVE 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.