CVE-2026-96640

Description

Pillow is a Python imaging library. From 5.1.0 until 13.0.0, PdfParser.linearize_page_tree() in src/PIL/PdfParser.py treats a PDF /Pages graph as a tree without tracking duplicate indirect references. When Image.save(..., format="PDF", append=True) processes an attacker-controlled existing PDF whose /Kids arrays repeatedly reference the same child /Pages node, Pillow expands the shared subtree as distinct pages. A compact malformed PDF can therefore create exponentially many page references and consume disproportionate CPU before the append completes. This issue is fixed in version 13.0.0.

References

https://github.com/python-pillow/Pillow/security/advisories/GHSA-mrfp-p49p-3hf2

https://github.com/python-pillow/Pillow/releases/tag/13.0.0

https://github.com/python-pillow/Pillow/pull/10093

https://github.com/python-pillow/Pillow/commit/6f0e7ee1f9c2fe227906f8a4b926e6622b702bc7

Details

Source: Mitre, NVD

Risk Information

CVSS v2

CVSS v3

CVSS v4