CVE-2025-0906: PDF-XChange Editor Information Disclosure

CVE-2025-0906 Overview

CVE-2025-0906 is an out-of-bounds read vulnerability in PDF-XChange Editor's JB2 file parsing logic. The flaw allows remote attackers to disclose sensitive information from the memory of affected installations. Exploitation requires user interaction: the victim must open a crafted file or visit a malicious page that delivers one.

The vulnerability was reported through the Trend Micro Zero Day Initiative as ZDI-CAN-25434 and tracked publicly as ZDI-25-068. Attackers can chain this issue with other vulnerabilities to achieve arbitrary code execution in the context of the current process.

Critical Impact

An attacker can leak adjacent process memory and combine the leak with secondary flaws to execute arbitrary code in the user's security context.

Affected Products

• PDF-XChange Editor (all versions prior to the vendor fix referenced in ZDI-25-068)
• PDF-XChange PRO bundle components that ship the Editor binary
• Any third-party application embedding the affected JB2 parser

Discovery Timeline

• 2025-02-11 - CVE-2025-0906 published to NVD
• 2025-02-12 - Last updated in NVD database

Technical Details for CVE-2025-0906

Vulnerability Analysis

The vulnerability resides in the JB2 stream parser used by PDF-XChange Editor when rendering embedded image data inside PDF documents. JB2 is a bi-level image compression format commonly carried inside JBIG2 streams within PDFs. The parser fails to validate user-supplied length and offset fields against the size of the allocated buffer.

When the Editor processes a malformed JB2 segment, the read pointer advances past the end of the allocated heap region. The process then returns adjacent heap memory to higher-level rendering routines, exposing data that may include pointers, document content, or other application state. This behavior is classified under CWE-125 (Out-of-bounds Read).

Root Cause

The root cause is missing bounds validation on attacker-controlled fields inside JB2 segment headers. The parser trusts the encoded segment length and continues to read structured fields without confirming that the requested range falls within the allocated buffer. This produces a deterministic read past the buffer boundary whenever a victim opens a crafted file.

Attack Vector

Delivery requires user interaction. An attacker hosts a malicious PDF on a website, sends it as an email attachment, or stages it inside a shared document repository. When the victim opens the file in PDF-XChange Editor, the JB2 parser processes the embedded stream and triggers the out-of-bounds read. The disclosed memory can then be exfiltrated through embedded JavaScript actions or used as a primitive for a follow-on memory corruption exploit.

No verified public exploit code is available. The vulnerability is described in prose by the Zero Day Initiative Advisory ZDI-25-068.

Detection Methods for CVE-2025-0906

Indicators of Compromise

• PDF documents containing malformed JBIG2 or JB2 segments with length fields exceeding the encapsulating stream size
• Unexpected crashes or memory faults in PDFXEdit.exe shortly after opening a document from an external source
• Outbound network requests initiated by PDF-XChange Editor immediately after a document open event

Detection Strategies

• Inspect inbound PDF attachments at the mail gateway and flag files containing JBIG2 streams that fail structural validation
• Hunt for PDFXEdit.exe process telemetry showing access violations or anomalous child process creation
• Correlate PDF open events with subsequent script interpreter activity, such as JavaScript callbacks within the Editor

Monitoring Recommendations

• Enable application crash reporting and forward Windows Error Reporting (WER) events for PDF-XChange Editor to a central log store
• Track file-open telemetry for .pdf files originating from email, browsers, and removable media
• Alert on PDF-XChange Editor processes making network connections to non-vendor domains

How to Mitigate CVE-2025-0906

Immediate Actions Required

• Update PDF-XChange Editor to the latest version published by the vendor that addresses ZDI-25-068
• Restrict opening of PDFs originating from untrusted external sources until patching is complete
• Disable automatic PDF rendering in browsers and email clients configured to use PDF-XChange Editor

Patch Information

PDF-XChange has addressed the issue in the build referenced by Zero Day Initiative Advisory ZDI-25-068. Administrators should consult the vendor download portal for the current Editor release and deploy it through their standard software distribution channels. Verify the installed version after deployment to confirm the fix is in place.

Workarounds

• Configure email security gateways to strip or quarantine PDF attachments containing JBIG2 streams when patching is delayed
• Set an alternate default PDF viewer for high-risk user groups until the Editor is patched
• Apply application allow-listing policies that prevent PDF-XChange Editor from spawning script interpreters or shells

# Verify installed PDF-XChange Editor version on Windows endpoints
Get-ItemProperty "HKLM:\Software\Tracker Software\PDFXEditor\*" |
  Select-Object DisplayName, DisplayVersion, InstallLocation