Security readout for executives and security teams
Plain-English summary
CVE-2021-34835 affects Foxit PDF Reader 11.0.0.49893. A malicious PDF or webpage can trigger code execution after user interaction. Business risk is highest for staff who handle untrusted PDFs, such as finance, legal, HR, sales, and support.
Executive priority
Treat as high priority if Foxit PDF Reader 11.0.0.49893 exists in the environment. It requires user interaction, but PDF-based social engineering is common and the impact is arbitrary code execution on user workstations.
Technical view
The flaw is in Foxit PDF Reader handling of Annotation objects. The source describes missing validation of an object before operations are performed, mapped to CWE-416. Successful exploitation can execute code in the current process context with high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is limited to systems running Foxit PDF Reader 11.0.0.49893. This is an endpoint/client-side risk, not a directly internet-exposed server vulnerability. Users who open external PDFs or browse attacker-controlled pages are the likely target population.
Exploitation context
User interaction is required: the target must open a malicious file or visit a malicious page. The provided sources and KEV status do not show active exploitation. The vulnerability was reported as ZDI-CAN-14015 and later published as ZDI-21-917.
Researcher notes
The bundle does not provide exploit code, observed exploitation, or an exact fixed version. Validation should focus on version exposure and vendor bulletin alignment. Avoid assuming other Foxit products or versions are affected without separate vendor evidence.
Mitigation direction
- Inventory endpoints for Foxit PDF Reader 11.0.0.49893.
- Check Foxit security bulletins for the vendor-supported update or mitigation.
- Prioritize upgrades for users handling external PDFs.
- Restrict untrusted PDF handling where business workflow allows.
- Use endpoint controls to reduce impact from malicious document execution.
Validation and detection
- Confirm installed Foxit PDF Reader versions through endpoint management data.
- Verify patched or remediated systems no longer report version 11.0.0.49893.
- Review mail and web controls for risky PDF delivery paths.
- Confirm high-risk departments are included in remediation scope.
- Track exceptions with owner, justification, and review date.
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-2021-34835 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-21-917/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.