CVE-2026-57240 Overview
CVE-2026-57240 is a use-after-free vulnerability [CWE-416] affecting Foxit PDF Editor and Foxit PDF Reader on Microsoft Windows. When the application opens a PDF file and embedded JavaScript deletes PDF form fields, subsequent logic continues to reference the freed field pointers. These dangling pointers lead to invalid memory access and application crashes, with potential for arbitrary code execution in the context of the current user.
Attackers exploit the flaw by delivering a crafted PDF that a victim opens locally. The vulnerability requires user interaction but no authentication.
Critical Impact
A crafted PDF opened in Foxit PDF Editor or Reader can trigger use-after-free conditions, enabling attackers to crash the application or execute code with the user's privileges.
Affected Products
- Foxit PDF Editor on Microsoft Windows
- Foxit PDF Reader on Microsoft Windows
- Microsoft Windows platform installations of the above products
Discovery Timeline
- 2026-07-08 - CVE-2026-57240 published to NVD
- 2026-07-09 - Last updated in NVD database
Technical Details for CVE-2026-57240
Vulnerability Analysis
The flaw is a use-after-free condition classified under [CWE-416]. Foxit PDF Editor and Reader expose PDF form fields to embedded JavaScript through the document object model. When JavaScript calls a deletion routine against form fields, the underlying field objects are freed from the heap. However, the application retains stale pointers to those objects and dereferences them during later document processing.
Dereferencing a freed pointer produces undefined behavior. In the simplest case, the application crashes on an invalid read or write, causing a denial-of-service condition. In a controlled exploitation scenario, an attacker can reclaim the freed heap slot with attacker-controlled data, converting the dangling reference into a type confusion or arbitrary write primitive.
The vulnerability requires local file handling and user interaction, matching the local attack vector and confidentiality, integrity, and availability impact reflected in the CVSS scoring.
Root Cause
The root cause is missing pointer invalidation after PDF field objects are released by JavaScript. The application layer that manages field lifecycles does not synchronize with the object cache used by rendering, form processing, and event dispatch code paths. Stale references persist and are dereferenced later in the document lifecycle.
Attack Vector
An attacker crafts a PDF containing JavaScript that deletes one or more form fields during document initialization or in response to a scripted event. The attacker then delivers the file through email, a download link, or a shared drive. When the victim opens the PDF in Foxit PDF Editor or Reader, the application executes the embedded JavaScript, frees the field objects, and later dereferences the stale pointers. Successful heap grooming allows the attacker to gain code execution in the context of the current user.
No public proof-of-concept exploit or in-the-wild exploitation has been reported at the time of publication.
Detection Methods for CVE-2026-57240
Indicators of Compromise
- Unexpected crashes of FoxitPDFEditor.exe or FoxitPDFReader.exe with access violation error codes when opening PDF documents
- Windows Error Reporting (WER) entries referencing Foxit modules and heap corruption exceptions
- PDF files containing JavaScript that invokes field deletion APIs such as removeField immediately after document open
Detection Strategies
- Inspect inbound PDFs at the mail gateway and web proxy for embedded JavaScript that manipulates form fields during document open events
- Correlate process crash telemetry from EDR with the parent PDF filename and origin to identify malicious documents
- Hunt for Foxit processes spawning unexpected child processes such as cmd.exe, powershell.exe, or rundll32.exe
Monitoring Recommendations
- Enable verbose crash and exception logging for Foxit applications and forward events to a central SIEM or data lake
- Monitor endpoints for anomalous memory access violations in Foxit modules and alert on repeated occurrences from the same document
- Track PDF file provenance across email, browser downloads, and file shares to support post-incident scoping
How to Mitigate CVE-2026-57240
Immediate Actions Required
- Apply the vendor-provided security update from the Foxit Security Bulletins as soon as it is available for your installed version
- Restrict opening of PDF files from untrusted sources until affected endpoints are patched
- Disable JavaScript execution in Foxit PDF Editor and Reader through application preferences to break the exploitation path
Patch Information
Foxit publishes fixes for its PDF Editor and PDF Reader products through the Foxit Security Bulletins page. Administrators should identify the fixed build for their installed edition and deploy it across all Windows endpoints running the affected products. Verify remediation by checking the application version after update.
Workarounds
- Disable JavaScript in Foxit PDF Editor and Reader via Preferences > JavaScript > Enable JavaScript Actions until patched
- Block or quarantine PDF attachments from external senders at the email gateway
- Enforce least-privilege user accounts to limit the impact of code execution in the context of the Foxit process
# Configuration example: disable JavaScript via registry on Windows endpoints
reg add "HKCU\Software\Foxit Software\Foxit PDF Editor\Preferences\JavaScript" /v "bEnableJS" /t REG_DWORD /d 0 /f
reg add "HKCU\Software\Foxit Software\Foxit PDF Reader\Preferences\JavaScript" /v "bEnableJS" /t REG_DWORD /d 0 /f
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
