Security readout for executives and security teams
Plain-English summary
CVE-2021-34843 is a high-severity Foxit PDF Reader flaw that can let an attacker run code if a user opens a malicious PDF or visits a malicious page. The risk is highest where Foxit PDF Reader 11.0.0.49893 is installed on endpoints handling untrusted documents.
Executive priority
Treat as a targeted endpoint remediation item. It is not proven actively exploited in the provided sources, but successful exploitation could compromise user workstations and sensitive documents.
Technical view
The flaw affects Foxit PDF Reader 11.0.0.49893 in Annotation object handling. Sources describe missing validation that an object exists before operations are performed, mapped to CWE-416, allowing arbitrary code execution in the current process after user interaction.
Likely exposure
Exposure is limited to installations of Foxit PDF Reader 11.0.0.49893, especially user workstations where PDFs from email, web downloads, or external parties are opened.
Exploitation context
The source bundle does not show CISA KEV listing or active exploitation evidence. Exploitation requires user interaction: opening a malicious file or visiting a malicious page.
Researcher notes
Key evidence comes from ZDI-CAN-14025 and CVE data. The available bundle identifies the vulnerable version and flaw class, but does not provide a specific fixed version or confirmed exploitation status.
Mitigation direction
- Inventory endpoints for Foxit PDF Reader 11.0.0.49893.
- Check Foxit security bulletins for the vendor-approved update or mitigation.
- Prioritize remediation on endpoints handling external PDFs.
- Limit opening untrusted PDFs until vendor guidance is applied.
- Reinforce user caution around unexpected PDF attachments and links.
Validation and detection
- Confirm installed Foxit PDF Reader versions across managed endpoints.
- Verify affected systems are updated according to Foxit guidance.
- Review endpoint detections involving suspicious PDF activity.
- Check email and web controls for untrusted PDF delivery paths.
- Document residual systems that cannot be remediated quickly.
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-2021-34843 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-21-925/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.