Security readout for executives and security teams
Plain-English summary
CVE-2021-34963 is a high-severity flaw in Foxit PDF Editor that can let an attacker run code if a user opens a malicious PDF or visits a malicious page. The provided sources do not show active exploitation, but the impact is serious because execution occurs in the user's Foxit process.
Executive priority
Treat this as a workstation patching priority for teams that use Foxit PDF Editor. It is not wormable, but user-assisted code execution from malicious PDFs can support phishing-driven compromise. Prioritize exposed users handling external documents.
Technical view
The flaw is a CWE-416 use-after-free in handling PolyLine Annotation objects. Foxit PDF Editor fails to validate that an Annotation object still exists before operating on it. ZDI reports this can lead to arbitrary code execution in the current process. CVSS is 7.8 with required user interaction.
Likely exposure
Exposure is limited to installations of Foxit PDF Editor 11.0.0.49893 identified in the sources. Risk is highest on endpoints where users open PDFs from email, web downloads, customer submissions, or other untrusted sources.
Exploitation context
The sources state exploitation requires user interaction: the target must open a malicious file or visit a malicious page. The CVE is not listed as KEV in the provided bundle, and no provided source confirms active exploitation.
Researcher notes
Public details identify the vulnerable object class and bug type but do not provide a fixed version in the supplied bundle. Avoid assuming exploit availability. Validation should focus on product/version presence, document-handling exposure, and vendor bulletin confirmation.
Mitigation direction
- Inventory endpoints for Foxit PDF Editor 11.0.0.49893.
- Check Foxit security bulletins for the vendor-approved fixed version or mitigation.
- Upgrade affected Foxit PDF Editor installations according to vendor guidance.
- Restrict opening PDFs from untrusted sources until remediation is complete.
- Use endpoint controls to limit impact from user-context code execution.
Validation and detection
- Confirm whether Foxit PDF Editor 11.0.0.49893 is installed in endpoint inventory.
- Compare installed versions against Foxit security bulletin guidance.
- Review email and web security telemetry for malicious PDF delivery attempts.
- Verify patched endpoints no longer report the affected version.
- Confirm no unsupported Foxit PDF Editor installations remain.
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-2021-34963 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
- ZDI-21-1194CVE reference · x_research-advisory
- vendor-provided URLCVE reference · vendor-advisory
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.