Security readout for executives and security teams
Plain-English summary
A malicious PDF or webpage could make vulnerable Foxit PDF Reader run attacker-controlled code as the logged-in user. Exploitation requires a user to open a malicious file or visit a malicious page. The bundle names Foxit PDF Reader 11.0.0.49893 and does not show confirmed active exploitation.
Executive priority
Treat this as a high-priority endpoint remediation issue, especially for users who receive external PDFs. It is not evidenced as actively exploited in this bundle, but successful exploitation could run code under the user's session and support broader compromise.
Technical view
CVE-2021-34838 is a high-severity RCE in Foxit PDF Reader's Annotation object handling. The flaw is described as missing validation that an object exists before operations occur, mapped to CWE-416. Successful exploitation can affect confidentiality, integrity, and availability in the current process context.
Likely exposure
Exposure is most likely on endpoints where Foxit PDF Reader 11.0.0.49893 is installed and users can open PDFs or browse attacker-controlled content. Servers are only likely exposed if they process PDFs using the affected desktop product, which the source bundle does not establish.
Exploitation context
The sources describe user-assisted exploitation, not automatic network compromise. The target must open a malicious file or visit a malicious page. CISA KEV status is false in the bundle, so active exploitation is not evidenced here.
Researcher notes
ZDI identifies this as ZDI-CAN-14019 and locates the flaw in Annotation object handling. The record indicates local attack vector, low complexity, no privileges required, and user interaction required. The bundle does not provide patch-version details or proof-of-concept material.
Mitigation direction
- Identify and prioritize hosts running Foxit PDF Reader 11.0.0.49893.
- Check Foxit security bulletins for the vendor-approved fixed version or mitigation.
- Upgrade affected installations according to Foxit guidance.
- Restrict untrusted PDF handling until affected endpoints are remediated.
- Use email and web filtering to reduce malicious document delivery risk.
Validation and detection
- Confirm installed Foxit PDF Reader versions through endpoint inventory or software management.
- Check vulnerability scanner findings specifically for CVE-2021-34838.
- Verify remediated hosts no longer report version 11.0.0.49893.
- Review user groups with frequent external PDF exposure for prioritization.
- Confirm controls block or warn on untrusted PDF attachments and links.
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-2021-34838 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-21-920/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.