CVE-2026-57242 Overview
CVE-2026-57242 is a use-after-free vulnerability [CWE-416] in Foxit PDF Editor and Foxit PDF Reader on Microsoft Windows. When the application opens a PDF containing JavaScript that modifies a form, related page objects lack complete lifecycle management and null value validation. As the page state changes, the application continuously dereferences invalid objects, leading to a crash and potential code execution in the context of the current user.
Critical Impact
A crafted PDF can trigger memory corruption in Foxit PDF Editor and Reader, allowing an attacker to execute arbitrary code with the privileges of the user opening the file.
Affected Products
- Foxit PDF Editor on Microsoft Windows
- Foxit PDF Reader on Microsoft Windows
- Microsoft Windows platforms hosting Foxit PDF applications
Discovery Timeline
- 2026-07-08 - CVE-2026-57242 published to NVD
- 2026-07-09 - Last updated in NVD database
Technical Details for CVE-2026-57242
Vulnerability Analysis
The defect is a use-after-free condition triggered through the JavaScript engine that Foxit exposes to PDF documents. When a document script modifies a form field, the application maintains references to page-level objects that back the form and its rendering context. These related objects do not receive complete lifecycle management, and the code path does not perform null value validation before dereferencing them.
When the page state changes, for example through form updates, navigation, or re-rendering, the underlying object can be released while other components still hold pointers to it. The application then continuously dereferences these invalid pointers, producing a crash. An attacker who controls the freed memory region can steer execution to attacker-supplied data.
Root Cause
The root cause is missing object lifecycle tracking between the JavaScript form-manipulation layer and the page rendering layer. Objects freed during page state transitions are not invalidated in dependent references, and dereferences proceed without null checks, matching the pattern described by [CWE-416].
Attack Vector
Exploitation requires local user interaction. The victim must open a malicious PDF in a vulnerable Foxit PDF Editor or Reader build on Windows. The document contains JavaScript that modifies a form and induces the page state change needed to free and then reuse the tracked object. No prior privileges are required, and successful exploitation yields high impact to confidentiality, integrity, and availability of the user session.
No verified public proof-of-concept code is available. See the Foxit Security Bulletins for vendor technical details.
Detection Methods for CVE-2026-57242
Indicators of Compromise
- Unexpected crashes of FoxitPDFEditor.exe or FoxitPDFReader.exe immediately after opening a PDF that contains JavaScript form actions.
- Windows Error Reporting entries citing access violations inside Foxit modules following PDF open events.
- PDF files delivered via email or download that embed /JS or /JavaScript objects invoking form field modifications on document open.
Detection Strategies
- Inspect inbound PDFs for embedded JavaScript that alters form fields during OpenAction or page-change events.
- Correlate process crash telemetry from Foxit binaries with recent file-open activity to identify targeted document delivery.
- Hunt for child processes spawned by Foxit PDF Editor or Reader, which would indicate post-exploitation code execution.
Monitoring Recommendations
- Enable endpoint telemetry for file writes, module loads, and child process creation under Foxit application processes.
- Alert on Foxit processes making outbound network connections shortly after document open.
- Track WER and application crash dumps referencing Foxit modules for triage against this CVE.
How to Mitigate CVE-2026-57242
Immediate Actions Required
- Update Foxit PDF Editor and Foxit PDF Reader on all Windows endpoints to the version identified in the vendor bulletin.
- Restrict opening of PDFs from untrusted sources, and block PDF attachments at the email gateway when practical.
- Disable JavaScript execution in Foxit PDF Editor and Reader through application preferences until patches are deployed.
Patch Information
Refer to the Foxit Security Bulletins for the fixed build numbers and download links for Foxit PDF Editor and Foxit PDF Reader on Windows.
Workarounds
- Turn off JavaScript in Foxit under Preferences → JavaScript by clearing Enable JavaScript Actions.
- Enable Safe Reading Mode to block untrusted actions embedded in PDFs.
- Apply application allowlisting so only patched Foxit binaries execute on managed endpoints.
# Configuration example: disable Foxit JavaScript via registry on Windows
reg add "HKCU\Software\Foxit Software\Foxit PDF Editor\Preferences\JavaScript" /v bJSEnable /t REG_DWORD /d 0 /f
reg add "HKCU\Software\Foxit Software\Foxit PDF Reader\Preferences\JavaScript" /v bJSEnable /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.
