CVE-2026-5942 Overview
CVE-2026-5942 is a Use After Free vulnerability affecting Foxit PDF Reader and PDF Editor. Flaws in page lifecycle management allow document structure changes to desynchronize internal component states, causing subsequent operations to access invalidated objects and crash the program. This vulnerability requires user interaction, as a victim must open a specially crafted PDF document to trigger the flaw.
Critical Impact
Attackers can craft malicious PDF documents that exploit the page lifecycle management flaw to cause application crashes and denial of service when opened by unsuspecting users.
Affected Products
- Foxit PDF Editor
- Foxit PDF Reader
Discovery Timeline
- April 27, 2026 - CVE-2026-5942 published to NVD
- April 29, 2026 - Last updated in NVD database
Technical Details for CVE-2026-5942
Vulnerability Analysis
This vulnerability is classified as CWE-416 (Use After Free), a memory corruption vulnerability that occurs when a program continues to use a pointer after the memory it references has been freed. In the context of Foxit PDF Reader and Editor, the vulnerability manifests in the page lifecycle management system.
When processing PDF documents with specific document structure modifications, the application fails to properly synchronize internal component states. This desynchronization causes the application to reference memory objects that have already been deallocated, leading to undefined behavior. The local attack vector requires user interaction—specifically, a victim must open a maliciously crafted PDF file.
The vulnerability primarily impacts availability, as successful exploitation results in application crashes and denial of service. There is no evidence of confidentiality or integrity impact based on the current analysis.
Root Cause
The root cause lies in improper memory management within Foxit's page lifecycle handling code. When document structure changes occur, internal component states are not properly updated to reflect the new memory allocation status. This creates a race condition where operations continue to reference objects that have been invalidated, resulting in use-after-free conditions.
The desynchronization occurs because the lifecycle management system does not implement adequate validation checks to ensure object references remain valid after structural modifications to the PDF document.
Attack Vector
The attack requires local access and user interaction. An attacker would need to:
- Craft a malicious PDF document with specific structural elements designed to trigger the lifecycle desynchronization
- Distribute the malicious PDF through phishing emails, compromised websites, or other social engineering techniques
- Wait for a victim to open the document in a vulnerable version of Foxit PDF Reader or Editor
The vulnerability mechanism involves manipulating document structure in ways that cause internal component states to become desynchronized. When subsequent operations attempt to access these invalidated objects, the application crashes due to accessing freed memory. Technical details for exploitation can be found in the Foxit Security Bulletin.
Detection Methods for CVE-2026-5942
Indicators of Compromise
- Unexpected crashes of Foxit PDF Reader or Editor when opening PDF documents
- PDF files with unusual document structure modifications or malformed page lifecycle elements
- Repeated application crashes associated with specific PDF files from untrusted sources
Detection Strategies
- Monitor for abnormal termination of FoxitPDFReader.exe or FoxitPDFEditor.exe processes
- Implement endpoint detection rules for memory access violations in Foxit applications
- Deploy PDF content inspection at email gateways to identify malformed documents
- Use application crash telemetry to identify patterns of exploitation attempts
Monitoring Recommendations
- Enable crash reporting and analysis for Foxit PDF applications across the enterprise
- Monitor process behavior for signs of memory corruption exploitation
- Implement logging for PDF file opens from external or untrusted sources
- Configure SentinelOne to monitor for suspicious document-based attack patterns
How to Mitigate CVE-2026-5942
Immediate Actions Required
- Update Foxit PDF Reader and PDF Editor to the latest available versions
- Review and restrict PDF file handling policies from untrusted sources
- Enable Protected Mode or sandboxing features if available in Foxit applications
- Educate users about the risks of opening PDF files from unknown sources
Patch Information
Foxit has released security updates to address this vulnerability. Users should consult the Foxit Security Bulletin for specific version information and download the latest patches. Organizations should prioritize updating all instances of Foxit PDF Reader and PDF Editor across their environment.
Workarounds
- Use alternative PDF readers for documents from untrusted sources until patches are applied
- Implement email attachment scanning and filtering for PDF files
- Consider disabling JavaScript in Foxit PDF applications to reduce attack surface
- Deploy application whitelisting to prevent execution of malicious payloads
# Example: Check installed Foxit version (Windows)
# Navigate to Help > About in Foxit PDF Reader/Editor
# Compare version against patched versions in security bulletin
# Or check via PowerShell:
Get-ItemProperty "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\*" |
Where-Object { $_.DisplayName -like "*Foxit*" } |
Select-Object DisplayName, DisplayVersion
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
