CVE-2022-38928

What it actually does

Null pointer dereference in FoFiType1C.cc:2393 during parsing of Type1C font data in a PDF document, resulting in memory corruption that can be leveraged for arbitrary code execution.

Why it matters to the business

Attackers can fully compromise systems used to view PDF files with the affected software, leading to data theft, ransomware deployment, or persistent access; the absence of listed fixed versions increases exposure for organizations relying on this viewer.

How an attack unfolds

An attacker crafts a PDF containing malformed Type1C font data that triggers the null dereference when opened locally in the vulnerable viewer; with an exploit already public, the flaw can be used to execute arbitrary code under the privileges of the user who opens the document.

How to fix it

Replace the affected XPDF installation with a version that resolves the null dereference; if no patched release is available, migrate to an alternative PDF viewer and restrict use of the vulnerable binary until a fix is confirmed.

How to confirm the fix worked

Confirm the installed XPDF binary version is newer than 4.04 and test opening of known trigger PDFs in a controlled environment; monitor vendor release notes for explicit mention of the FoFiType1C.cc fix.

Typical attack path

1. Attacker creates a malicious PDF embedding specially malformed Type1C font structures.
2. Victim receives the PDF via email, download, or shared storage.
3. Victim opens the file using the vulnerable XPDF viewer on a local system.
4. The parser reaches the defective code path and dereferences a null pointer.
5. Memory corruption is exploited to achieve code execution or system control.

How to detect it

Review file-access and process-creation logs for XPDF executions immediately preceding crashes or unexpected child processes; look for PDF files that cause segmentation faults or abnormal memory behavior when parsed.

What your security team should do

• Immediately inventory all systems running XPDF 4.04 or earlier and block execution where possible.
• Replace the viewer with a maintained alternative and update organizational policy to prohibit use of unpatched PDF tools.
• Hunt for any historical PDF files that match the malformed Type1C pattern using available forensic tools.