Security readout for executives and security teams
Plain-English summary
CVE-2021-34836 affects 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 user running Foxit, making this a serious endpoint risk where vulnerable Reader versions remain installed.
Executive priority
Prioritize remediation where Foxit Reader is deployed to users handling external documents. This is high severity but not proven actively exploited in the provided sources, so urgency should be risk-based and focused on exposed endpoints.
Technical view
The flaw is in Foxit PDF Reader Annotation object handling. The CVE describes missing validation of an object before operations, mapped to CWE-416, allowing arbitrary code execution in the current process. CVSS is 7.8 high with required user interaction and no privileges required.
Likely exposure
Exposure is most likely on endpoints with Foxit PDF Reader 11.0.0.49893 installed, especially users who receive external PDFs or browse untrusted content. The source bundle names only this version, so broader version exposure is not established here.
Exploitation context
The CVE requires user interaction: opening a malicious file or visiting a malicious page. The source bundle does not indicate CISA KEV listing or active exploitation evidence. Treat exploit status as unconfirmed based on the provided sources.
Researcher notes
ZDI tracked this as ZDI-CAN-14017 and ZDI-21-918. The public description identifies Annotation object handling and object validation failure but does not provide patch version details in the bundle. Avoid assuming affected versions beyond Foxit PDF Reader 11.0.0.49893.
Mitigation direction
- Identify and prioritize Foxit PDF Reader 11.0.0.49893 installations.
- Check Foxit security bulletins for the vendor-fixed build and upgrade guidance.
- Reduce handling of untrusted PDFs on affected endpoints until remediated.
- Use email and web filtering to reduce malicious PDF delivery risk.
- Monitor vendor advisories for any updated remediation details.
Validation and detection
- Inventory endpoint software for Foxit PDF Reader 11.0.0.49893.
- Confirm remediated systems no longer run the affected build.
- Review email and web security logs for suspicious PDF delivery attempts.
- Review endpoint alerts involving unusual Foxit Reader process behavior.
- Document any remaining vulnerable endpoints with owner and remediation 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-2021-34836 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-21-918/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.