CVE-2024-3247

What it actually does

A PDF containing a circular reference loop inside an object stream triggers unbounded recursion during parsing, exhausting the call stack and causing a crash.

Why it matters to the business

Processing a crafted PDF with Xpdf can crash the viewer or any application embedding it, interrupting document workflows and requiring restarts or manual intervention.

How an attack unfolds

An attacker creates a malicious PDF with self-referential objects inside an object stream; when the file is opened or parsed by Xpdf the infinite recursion occurs and the process terminates.

How to fix it

Upgrade Xpdf to a version that properly detects and terminates object loops during stream parsing; until then, avoid opening untrusted PDFs with the affected software.

How to confirm the fix worked

Confirm the installed Xpdf version is newer than 4.05 and test that a sample PDF with intentional object loops is rejected or handled without stack exhaustion.

Typical attack path

1. Craft a PDF containing an object stream with circular references
2. Deliver the file via email, web download, or shared storage
3. Victim or automated process opens the PDF with Xpdf or an embedding application
4. Parser enters infinite recursion and crashes the process

How to detect it

Review system and application logs for Xpdf segmentation faults or stack-overflow errors immediately after PDF file access; correlate with file-creation or download events involving PDFs.

What your security team should do

• Block or sandbox untrusted PDFs from reaching Xpdf installations until patched
• Monitor for Xpdf process crashes correlated with PDF file access
• Replace Xpdf with a maintained PDF library that includes loop detection if updates are unavailable