CVE-2024-9251: Foxit PDF Editor Use-After-Free Vulnerability

CVE-2024-9251 Overview

CVE-2024-9251 is a use-after-free vulnerability [CWE-416] in Foxit PDF Reader and Foxit PDF Editor on Windows. The flaw resides in the handling of PDF Annotation objects, where the application performs operations on an object without validating that it still exists. Remote attackers can leverage this weakness to disclose sensitive information from process memory. Exploitation requires user interaction: the target must open a malicious PDF file or visit a page that delivers one. Attackers can chain this issue with additional vulnerabilities to achieve arbitrary code execution in the context of the current process. The Zero Day Initiative tracked this issue as ZDI-CAN-24490 and published advisory ZDI-24-1306.

Critical Impact
Successful exploitation exposes sensitive process memory and can enable arbitrary code execution when combined with other vulnerabilities.

Affected Products

Foxit PDF Reader on Windows
Foxit PDF Editor on Windows
Windows installations processing untrusted PDF documents with Foxit products

Discovery Timeline

2024-11-22 - CVE-2024-9251 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-9251

Vulnerability Analysis

The vulnerability is a use-after-free condition in the Annotation object handling code of Foxit PDF Reader and Editor. PDF annotations are interactive elements embedded in documents, including comments, form fields, and links. Foxit's parser fails to confirm that an annotation object is still allocated before operating on it. When the object has been freed but a stale reference remains, subsequent access reads from memory that may now contain attacker-influenced or sensitive data. This class of flaw commonly produces information disclosure primitives that leak pointers, heap metadata, or object contents, which attackers use to defeat address space layout randomization and stage follow-on exploits.

Root Cause

The root cause is the lack of object lifetime validation prior to dereferencing an Annotation object pointer. The application code path performs operations on the object without checking whether it has been released. This dangling reference produces the classic use-after-free pattern tracked as [CWE-416].

Attack Vector

The attack requires local user interaction. An attacker crafts a malicious PDF that manipulates annotation object lifetimes and delivers it through phishing email, drive-by download, or a compromised website. When the victim opens the file in Foxit PDF Reader or Editor, the crafted annotation triggers the use-after-free and leaks memory contents. Because the vulnerability yields information disclosure, adversaries typically pair it with a memory-corruption bug to achieve arbitrary code execution. Refer to the Zero Day Initiative Advisory ZDI-24-1306 for technical details.

Detection Methods for CVE-2024-9251

Indicators of Compromise

PDF files containing malformed or unusual annotation objects such as /Annot entries that manipulate object references or lifetimes.
Unexpected child processes spawned by FoxitPDFReader.exe or FoxitPDFEditor.exe, including command shells or scripting hosts.
Foxit process crashes or exception events in the Windows Application log immediately after opening a PDF from an untrusted source.

Detection Strategies

Inspect inbound email attachments and web downloads with static PDF analyzers that flag suspicious annotation structures and JavaScript actions.
Enable endpoint behavioral detection to alert on document readers accessing unrelated memory regions, injecting into other processes, or performing network callbacks.
Correlate Foxit application crash telemetry with recent PDF open events to identify potential exploitation attempts.

Monitoring Recommendations

Forward Sysmon Event IDs 1 (process creation) and 11 (file create) for Foxit binaries into your SIEM for continuous review.
Track outbound connections initiated by Foxit processes, which are unusual during normal PDF viewing.
Monitor the Foxit Security Bulletins page for updates and additional related advisories.

How to Mitigate CVE-2024-9251

Immediate Actions Required

Update Foxit PDF Reader and Foxit PDF Editor on Windows to the latest fixed release listed in the Foxit Security Bulletins.
Restrict opening of PDF files received from untrusted sources until patches are deployed across the fleet.
Enforce application allowlisting to prevent Foxit processes from spawning shells or scripting interpreters.

Patch Information

Foxit has released fixed versions for both PDF Reader and PDF Editor on Windows. Consult the Foxit Security Bulletins and ZDI-24-1306 for the exact fixed build numbers and apply the update through Foxit's built-in updater or enterprise deployment tooling.

Workarounds

Disable JavaScript execution inside Foxit PDF Reader and Editor via Preferences to reduce annotation-driven attack surface.
Configure Safe Reading Mode and Trust Manager to block unverified actions on PDF files from external sources.
Route PDF viewing through an alternate reader in an isolated browser sandbox or virtual machine for high-risk documents until patching is complete.

bash

# Configuration example: enforce Foxit Safe Reading Mode via registry on Windows
reg add "HKCU\Software\Foxit Software\Foxit PDF Reader\Preferences\Trust Manager" /v bSafeMode /t REG_DWORD /d 1 /f
reg add "HKCU\Software\Foxit Software\Foxit PDF Reader\Preferences\JavaScript" /v bEnableJS /t REG_DWORD /d 0 /f