Security readout for executives and security teams
Plain-English summary
CVE-2021-34842 is a high-severity code execution flaw in Foxit PDF Reader 11.0.0.49893. An attacker would need a user to open a malicious file or visit a malicious page, after which code could run with that user’s application privileges.
Executive priority
Prioritize remediation on employee workstations that process external documents. The business risk is phishing-driven code execution, with potential data access or workstation compromise, but no active exploitation is evidenced in the supplied sources.
Technical view
The flaw is in Foxit PDF Reader Annotation object handling. The source describes missing validation of an object’s existence before operations, mapped to CWE-416. Successful exploitation can execute arbitrary code in the current process with high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is likely limited to endpoints running Foxit PDF Reader 11.0.0.49893. Risk is higher for users who handle external PDFs, email attachments, downloads, or browser-delivered documents.
Exploitation context
The source bundle does not show CISA KEV listing or cited active exploitation. Exploitation requires user interaction: opening a malicious file or visiting a malicious page. Treat this as credible phishing and document-delivery risk, not proven in-the-wild exploitation.
Researcher notes
Key gaps: the source bundle identifies the affected version and impact, but does not provide a fixed version or detailed vendor mitigation text. Use Foxit’s advisory as the authoritative source for patch mapping and deployment verification.
Mitigation direction
- Inventory endpoints for Foxit PDF Reader 11.0.0.49893.
- Update affected installations according to Foxit security bulletin guidance.
- Restrict opening untrusted PDFs until affected installations are remediated.
- Use endpoint controls to reduce exposure to externally delivered malicious documents.
Validation and detection
- Confirm whether Foxit PDF Reader 11.0.0.49893 is installed.
- Verify patched or non-affected versions after remediation.
- Review endpoint telemetry for suspicious Foxit Reader crashes or child processes.
- Confirm controls block or warn on untrusted PDF attachments and downloads.
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.
CWE-416: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution 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-2021-34842 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
- High
- CVSS
- 7.8 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
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 vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H1.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
7.8HighVector: CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://www.foxit.com/support/security-bulletins.htmlCVE reference · x_refsource_MISC
- https://www.zerodayinitiative.com/advisories/ZDI-21-924/CVE 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.
Use After Free
Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.