CVE-2025-2231: PDF-XChange Editor RTF Parsing RCE Flaw

CVE-2025-2231 Overview

CVE-2025-2231 is an out-of-bounds read vulnerability [CWE-125] in PDF-XChange Editor and PDF-Tools version 10.5.1.394. The flaw resides in the parsing logic for Rich Text Format (RTF) files. Attackers can exploit it to execute arbitrary code in the context of the current user process. Exploitation requires user interaction: the target must open a malicious RTF file or visit a malicious page that delivers one. The Zero Day Initiative tracked the issue as ZDI-CAN-25473 and assigned advisory ZDI-25-129.

Critical Impact
Successful exploitation allows arbitrary code execution in the context of the current user, compromising confidentiality, integrity, and availability on the host.

Affected Products

PDF-XChange Editor 10.5.1.394
PDF-XChange PDF-Tools 10.5.1.394
Workflows that automatically render or convert RTF files through these products

Discovery Timeline

2025-03-24 - CVE-2025-2231 published to the National Vulnerability Database
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-2231

Vulnerability Analysis

The vulnerability exists in the RTF file parser embedded within PDF-XChange Editor and PDF-Tools. The parser fails to properly validate user-supplied length or offset values before performing read operations against an allocated buffer. When a crafted RTF structure is processed, the parser reads past the end of the buffer. This out-of-bounds read returns memory contents the parser interprets as control data. Attackers can shape these reads to influence subsequent program flow and ultimately gain code execution in the running process.

Because the attack vector is local and requires user interaction, exploitation typically depends on social engineering. A user must open a malicious RTF file or trigger the document handler through a browser or email client integration. Once triggered, code runs at the privilege level of the user invoking the application.

Root Cause

The root cause is missing bounds validation on user-controlled fields within the RTF stream. The parser computes a read offset from attacker-influenced header data without verifying that the offset remains within the allocated buffer. This maps to the Common Weakness Enumeration class [CWE-125] Out-of-Bounds Read.

Attack Vector

The attacker delivers a crafted RTF file through phishing, drive-by download, or shared file storage. When PDF-XChange Editor or PDF-Tools parses the file, the out-of-bounds read fires. The attacker leverages adjacent memory contents and parser state to corrupt control data and pivot to code execution. No authentication is required, but the victim must actively open the file.

No public proof-of-concept exploit is currently available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. Refer to the Zero Day Initiative Advisory ZDI-25-129 for additional technical details.

Detection Methods for CVE-2025-2231

Indicators of Compromise

Unexpected child processes spawned by PDFXEdit.exe or PDFXTools.exe, particularly command interpreters such as cmd.exe or powershell.exe
Crashes or access violation events recorded against PDF-XChange binaries when handling .rtf attachments
RTF files arriving via email or download whose internal structure deviates from standard RTF control word usage
Outbound network connections initiated by PDF-XChange processes immediately after opening a document

Detection Strategies

Monitor process creation telemetry for PDF-XChange binaries launching scripting hosts, LOLBins, or unsigned executables
Inspect email gateways and web proxies for RTF attachments delivered alongside PDF lures targeting PDF-XChange users
Deploy YARA rules that flag malformed RTF control word lengths and oversized object data segments

Monitoring Recommendations

Enable Windows Defender Application Control or AppLocker logging for execution events originating from document reader processes
Centralize endpoint detection telemetry to correlate document-open events with subsequent process and network activity
Track installed versions of PDF-XChange Editor and PDF-Tools across managed endpoints to confirm patch coverage

How to Mitigate CVE-2025-2231

Immediate Actions Required

Upgrade PDF-XChange Editor and PDF-Tools to the fixed version listed in the PDF-XChange Security Bulletins
Block inbound RTF attachments at email gateways or quarantine them pending sandbox analysis
Restrict the ability of standard users to open RTF files with PDF-XChange products through file association policies
Educate users to avoid opening unsolicited RTF documents, even when delivered alongside legitimate PDF content

Patch Information

PDF-XChange has published fixed builds via its security bulletin page. Administrators should consult the PDF-XChange Security Bulletins to identify the build that addresses CVE-2025-2231 and deploy it across all installations of version 10.5.1.394 and earlier.

Workarounds

Change the default handler for .rtf files to a non-vulnerable application such as a hardened text viewer
Disable RTF parsing within PDF-XChange via group policy or administrative configuration where supported
Run PDF-XChange Editor and PDF-Tools inside an application sandbox or restricted user context to limit blast radius
Apply attack surface reduction rules that block Office and document readers from creating child processes

bash

# Example: Remove .rtf association from PDF-XChange Editor on Windows
reg delete "HKCU\Software\Classes\.rtf\OpenWithProgids" /v "PDFXEdit.RTF" /f
assoc .rtf=txtfile