Pillow PDF append accepts malformed shared page-tree DAG causing resource exhaustion

[ Description ]Official 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.

[ Fixes ]Fixes and patches

• Pillow 13.0.0Fixed version · GitHub Advisories · pip package Pillow: upgrade to 13.0.0 or later (affected >= 5.1.0, < 13.0.0)

[ Packages ]Affected open-source packages

• Pillow pipAffected >= 5.1.0, < 13.0.0 · fixed in 13.0.0 · GHSA-mrfp-p49p-3hf2

[ References ]References

• github.com/python-pillow/Pillow/commit/6f0e7ee1f9c2fe227906f8a4b926e6622b702bc7
• github.com/python-pillow/Pillow/pull/10093
• github.com/python-pillow/Pillow/releases/tag/13.0.0
• github.com/python-pillow/Pillow/security/advisories/GHSA-mrfp-p49p-3hf2