Security readout for executives and security teams
Plain-English summary
CVE-2021-34853 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. Successful exploitation could run code as the affected user, creating business risk on endpoints handling untrusted PDFs.
Executive priority
Treat this as a high-priority endpoint remediation item, not an emergency based on current evidence. Prioritize users exposed to external documents, legal, finance, HR, sales, and shared workstations.
Technical view
The flaw is in Foxit PDF Reader’s handling of Annotation objects. The source describes missing validation that an object exists before operations occur, mapped to CWE-416. Exploitation can lead to arbitrary code execution in the current process context, with CVSS 7.8 and user interaction required.
Likely exposure
Exposure is most likely on Windows endpoints running Foxit PDF Reader 11.0.0.49893, especially where users receive external PDFs or open PDF-linked web content. The bundle names no other affected Foxit products or versions.
Exploitation context
The source bundle does not show CISA KEV listing or other evidence of active exploitation. Exploitation requires user interaction: opening a malicious file or visiting a malicious page.
Researcher notes
Evidence supports affected product/version, vulnerability class, CVSS, and interaction requirement. The bundle does not provide a fixed version, detailed vendor remediation, proof-of-concept status, or active exploitation evidence.
Mitigation direction
- Inventory endpoints for Foxit PDF Reader 11.0.0.49893.
- Check Foxit security bulletins for fixed builds or vendor guidance.
- Prioritize updating systems that handle external PDFs.
- Limit use of affected Foxit versions until remediated.
- Maintain user caution around unexpected PDFs and links.
Validation and detection
- Confirm installed Foxit PDF Reader versions through endpoint inventory.
- Check whether any systems still run version 11.0.0.49893.
- Verify update status against Foxit security bulletin guidance.
- Review endpoint telemetry for unusual Foxit crashes or child processes.
- Document compensating controls where immediate update is delayed.
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-2021-34853 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-21-935/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.