When these image components declare conflicting subsampling values, the application triggers a faulty path in the non-samescale sub-byte-depth output logic. The system allocates a row buffer sized for packed output but proceeds to write a full byte per output column, regardless of the actual bit depth. This discrepancy leads to an out-of-bounds write that corrupts internal chunk-allocator metadata. Attackers can leverage this corruption to overwrite control structures or pointers, potentially achieving arbitrary code execution within the context of the user or service account running the Ghostscript binary.

Impact

Successful exploitation allows for arbitrary code execution on systems using Ghostscript for image or document processing. Given Ghostscript's common role as a backend component for web servers, document management systems, and print servers, the attack surface is significant. Exploitation can lead to full system compromise or unauthorized access to sensitive internal data processed by these applications.

Recommendation

Prioritized, concrete actions for detection engineering and security teams:

• Upgrade all installations of Ghostscript to version 10.08.0 or later immediately to patch CVE-2026-39919.
• Audit infrastructure to identify applications utilizing Ghostscript for PDF or image conversion, focusing on internet-facing web applications or document upload services.
• Implement restrictive sandboxing or containerization for processes invoking the Ghostscript binary to limit the impact of potential exploitation.