Security readout for executives and security teams
Plain-English summary
CVE-2021-39542 is a denial-of-service flaw in pdftools through 20200714. A crafted or malformed PDF can trigger a NULL pointer dereference in font handling, potentially crashing the tool. Business impact depends on whether pdftools processes untrusted PDFs in user-facing or automated workflows.
Executive priority
Treat this as a stability and service-continuity issue, not a confirmed data breach risk. Prioritize remediation where pdftools handles externally supplied PDFs or supports revenue, customer, or operational workflows.
Technical view
The CVE identifies Font::Size() in font.cpp as the affected function in pdftools through 20200714. The documented impact is denial of service from a NULL pointer dereference. The source bundle does not provide CVSS, CWE, patch details, or a complete affected-product matrix.
Likely exposure
Likely exposure is systems that run pdftools on PDFs from customers, email, web uploads, or automated ingestion. Internal-only use on trusted files lowers impact. The bundle lists no CPEs, package names, downstream distributions, or deployment-specific exposure indicators.
Exploitation context
The sources describe attacker-caused denial of service, but do not show active exploitation. CISA KEV status is false in the bundle. No public source in the bundle confirms exploitation in the wild, exploit maturity, or weaponized tooling.
Researcher notes
Evidence is limited to the CVE description and GitHub issue reference. The bundle does not identify a CVSS score, CWE, fixed commit, release advisory, or detailed affected CPEs. Validate findings against the upstream repository before making remediation commitments.
Mitigation direction
- Check vendor or repository guidance for fixed versions or recommended patches.
- Avoid processing untrusted PDFs with vulnerable pdftools builds where possible.
- Run PDF processing in isolated, restartable worker environments.
- Apply resource limits and monitoring around automated PDF pipelines.
- Add crash handling so failed PDF jobs do not disrupt broader services.
Validation and detection
- Inventory systems and pipelines that use pdftools.
- Confirm whether any installation is through 20200714.
- Identify workflows that accept PDFs from external or untrusted sources.
- Review crash logs for failures in font handling or pdftools processing.
- Verify compensating controls around isolation, retries, and service recovery.
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-2021-39542 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/leonhad/pdftools/issues/5CVE 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.