Security readout for executives and security teams
Plain-English summary
A crafted PDF or web page could make Foxit PDF Reader 11.0.0.49893 run attacker-controlled code when a user opens it. The attacker needs user interaction, but successful exploitation could grant the same access as the Reader process, risking data theft, tampering, or disruption.
Executive priority
Prioritize remediation for user workstations and teams that frequently receive PDFs from outside the organization. This is high severity because compromise can lead to code execution, but urgency is moderated by required user interaction and no cited active exploitation evidence.
Technical view
CVE-2021-34847 is a CWE-416 flaw in Foxit PDF Reader Annotation object handling. The product fails to validate that an object exists before operating on it. ZDI reports arbitrary code execution in the current process. CVSS 3.0 is 7.8 with user interaction required and high CIA impact.
Likely exposure
Exposure is limited to endpoints with Foxit PDF Reader 11.0.0.49893, especially where users open external PDFs or browse untrusted pages. The source bundle does not name other Foxit products or versions, so scope should not be expanded without vendor evidence.
Exploitation context
The provided sources require a malicious file or page and user interaction. The bundle says CISA KEV is false and provides no evidence of active exploitation. Treat exploitation as plausible but not confirmed in the wild from these sources.
Researcher notes
ZDI tracks this as ZDI-21-929 and CVE data links it to ZDI-CAN-14270. The source bundle identifies Annotation object handling and CWE-416, but does not include a proof of concept, exploit details, or a named fixed version.
Mitigation direction
- Identify and prioritize systems running Foxit PDF Reader 11.0.0.49893.
- Check Foxit security bulletins for the supported fixed version or vendor mitigation.
- Update or remove affected Foxit Reader installations according to vendor guidance.
- Limit opening untrusted PDFs until affected installations are remediated.
- Use endpoint controls to reduce damage from document-based code execution.
Validation and detection
- Inventory installed Foxit PDF Reader versions across managed endpoints.
- Confirm whether version 11.0.0.49893 is present.
- Review endpoint telemetry for suspicious Foxit Reader child processes or crashes.
- Verify users handling external PDFs are prioritized for remediation.
- Document exceptions where vendor guidance cannot be applied immediately.
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-2021-34847 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-21-929/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.