CVE-2024-9255 Overview
CVE-2024-9255 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 Annotation objects, where the application fails to validate that an object still exists before performing operations on it. An attacker can leverage this condition to execute arbitrary code in the context of the current process. Exploitation requires user interaction, such as opening a crafted PDF file or visiting a malicious page that serves the file. The vulnerability was reported through the Zero Day Initiative under identifier ZDI-CAN-25174 and disclosed as ZDI-24-1308.
Critical Impact
Successful exploitation allows arbitrary code execution with the privileges of the user running Foxit PDF Reader or Foxit PDF Editor.
Affected Products
- Foxit PDF Reader on Windows
- Foxit PDF Editor on Windows
- Documents processed through the vulnerable Annotation handling code path
Discovery Timeline
- 2024-11-22 - CVE-2024-9255 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2024-9255
Vulnerability Analysis
The vulnerability is a use-after-free condition in the Annotation object handling logic of Foxit PDF Reader and Foxit PDF Editor. The application performs operations on Annotation objects without first confirming that the underlying object is still valid in memory. When a referenced Annotation object has been freed but a stale pointer remains reachable, subsequent access reuses memory that may contain attacker-controlled data.
Because PDF Annotations can be manipulated through embedded JavaScript and interactive form actions, an attacker can script a precise sequence of object creation, deletion, and reuse. This gives the attacker control over the freed allocation and turns the dangling reference into a code execution primitive. The bug is triggered locally through a crafted document but does not require elevated privileges to reach.
Root Cause
The root cause is missing existence validation before dereferencing an Annotation object pointer. The application assumes the object remains allocated across operations, but a scripted sequence of Annotation modifications can free the object while a reference is still held. Foxit's Annotation handler then operates on freed memory, matching the classic pattern described by [CWE-416: Use After Free].
Attack Vector
An attacker delivers a malicious PDF through email, a compromised website, or a drive-by download. When the target opens the file in Foxit PDF Reader or Foxit PDF Editor, embedded logic manipulates Annotation objects to trigger the use-after-free. Control of the freed memory contents allows the attacker to hijack execution flow and run code with the current user's privileges. Full technical details are documented in the Zero Day Initiative Advisory ZDI-24-1308.
No public proof-of-concept exploit code is available at this time. The vulnerability mechanism is described in prose only; see the ZDI advisory for detailed reproduction information.
Detection Methods for CVE-2024-9255
Indicators of Compromise
- PDF files containing unusual JavaScript sequences that repeatedly create, delete, and reference Annotation objects
- Foxit PDF Reader or Foxit PDF Editor processes spawning unexpected child processes such as cmd.exe, powershell.exe, or rundll32.exe
- Crashes of FoxitPDFReader.exe or FoxitPDFEditor.exe with access violation exceptions in Annotation-related modules
- Outbound network connections initiated by the Foxit process shortly after a document is opened
Detection Strategies
- Monitor process lineage for Foxit PDF applications launching interpreters, script hosts, or shell binaries
- Alert on memory access violations and Data Execution Prevention (DEP) faults in Foxit processes handling PDF documents
- Inspect PDF documents at email and web gateways for suspicious JavaScript patterns targeting Annotation object lifecycles
Monitoring Recommendations
- Enable command-line and process-creation auditing on endpoints running Foxit products
- Capture file-open telemetry to correlate PDF documents with subsequent suspicious process behavior
- Retain crash dumps from Foxit applications for retrospective analysis of exploitation attempts
How to Mitigate CVE-2024-9255
Immediate Actions Required
- Update Foxit PDF Reader and Foxit PDF Editor to the fixed versions listed in the Foxit Security Bulletins
- Inventory all endpoints running Foxit products and prioritize patching for users who routinely handle external PDFs
- Block untrusted PDF attachments at email gateways until patches are deployed
Patch Information
Foxit has published fixed builds through its security bulletin process. Refer to the Foxit Security Bulletins page for the specific patched versions of Foxit PDF Reader and Foxit PDF Editor on Windows. Additional advisory details are available from the Zero Day Initiative Advisory ZDI-24-1308.
Workarounds
- Disable JavaScript execution in Foxit PDF Reader and Foxit PDF Editor through Preferences to reduce exposure to Annotation-manipulation scripts
- Open untrusted PDFs only in a sandboxed environment or an isolated virtual machine
- Enforce Attack Surface Reduction rules that block Office and reader applications from creating child processes
- Configure application allowlisting to prevent Foxit processes from executing unapproved binaries
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
