CVE-2026-57246 Overview
CVE-2026-57246 is a buffer-related vulnerability affecting Foxit PDF Editor and Foxit PDF Reader on Microsoft Windows. The flaw arises when the application processes abnormally constructed objects during signature verification. JavaScript embedded in a crafted PDF triggers the signature plugin, which then copies an abnormal string without performing proper argument validation. The missing validation causes memory to be handled unsafely, leading to an application crash and potential code execution in the context of the user. The issue is tracked under CWE-120: Buffer Copy without Checking Size of Input.
Critical Impact
A local attacker who convinces a user to open a malicious PDF can crash the application and potentially execute arbitrary code with the privileges of the current user.
Affected Products
- Foxit PDF Editor on Microsoft Windows
- Foxit PDF Reader on Microsoft Windows
- Microsoft Windows (host operating system)
Discovery Timeline
- 2026-07-08 - CVE-2026-57246 published to the National Vulnerability Database (NVD)
- 2026-07-09 - Last updated in NVD database
Technical Details for CVE-2026-57246
Vulnerability Analysis
The vulnerability resides in the signature verification path of the Foxit PDF signature plugin. When a PDF document contains an abnormally constructed object, the plugin fails to validate arguments before copying data. JavaScript inside the PDF invokes signature verification, and the plugin proceeds to copy the malformed string into a fixed-size buffer. Because size checks are absent, the copy operation writes beyond the intended memory boundary. The result is memory corruption that terminates the process and can be shaped by an attacker to influence execution flow. The CWE-120 classification identifies this as a classic buffer copy without size validation.
Root Cause
The root cause is missing input validation on string arguments passed to the signature plugin. The plugin trusts the length and structure of objects supplied by the parsed PDF and its embedded JavaScript. When the object is abnormal, the copy routine does not verify boundary conditions before writing to the destination buffer.
Attack Vector
Exploitation requires local access with user interaction. An attacker crafts a malicious PDF containing an abnormal object and JavaScript that triggers signature verification. The victim opens the PDF in Foxit PDF Editor or Foxit PDF Reader. The signature plugin processes the crafted object, copies the malformed string, and corrupts memory. Successful exploitation impacts confidentiality, integrity, and availability at the user's privilege level.
No verified public proof-of-concept code is available. Refer to the Foxit Security Bulletins for vendor-supplied technical details.
Detection Methods for CVE-2026-57246
Indicators of Compromise
- Unexpected crashes of FoxitPDFReader.exe or FoxitPDFEditor.exe shortly after opening a PDF document
- Windows Error Reporting (WerFault.exe) entries referencing Foxit signature plugin modules
- PDF files containing embedded JavaScript that invokes signature verification functions on malformed objects
Detection Strategies
- Inspect inbound PDF attachments and downloads for embedded JavaScript that invokes signatureSign, signatureValidate, or related signature APIs against abnormal object structures
- Correlate process crash events for Foxit binaries with recent file open activity to identify weaponized documents
- Apply YARA rules targeting PDF objects with malformed signature dictionaries and oversized string fields
Monitoring Recommendations
- Monitor endpoint telemetry for abnormal termination of Foxit PDF processes on Windows hosts
- Log and review PDF files delivered via email gateways and web proxies, focusing on documents containing signature-related JavaScript
- Alert on child process creation or unexpected DLL loads originating from Foxit PDF applications
How to Mitigate CVE-2026-57246
Immediate Actions Required
- Update Foxit PDF Editor and Foxit PDF Reader to the fixed versions listed in the vendor bulletin
- Restrict execution of JavaScript within PDF documents until patching is complete
- Educate users to avoid opening unsolicited PDF files, especially those containing digital signatures from unknown sources
Patch Information
Foxit has published fix information in its security advisory. Consult the Foxit Security Bulletins page to identify the specific patched versions of Foxit PDF Editor and Foxit PDF Reader, and deploy the updates across all affected Windows endpoints.
Workarounds
- Disable JavaScript in Foxit PDF Editor and Foxit PDF Reader via Preferences > JavaScript > Enable JavaScript Actions (uncheck) until updates are applied
- Disable or unload the signature plugin from the Foxit application's plugin manager if signature verification is not required
- Block delivery of PDF files from untrusted external senders at the email gateway
# Configuration example: disable JavaScript in Foxit via registry (Windows)
reg add "HKCU\Software\Foxit Software\Foxit PDF Reader\Preferences\JavaScript" /v bEnableJS /t REG_DWORD /d 0 /f
reg add "HKCU\Software\Foxit Software\Foxit PDF Editor\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.
