Resource exhaustion in Python-Pillow Pillow
CVE-2026-96640
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.
Vulnerability class: DoS (Denial of Service)
Published · last modified .
EPSS exploit prediction
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Affected products
- Python-Pillow Pillow — versions >= 5.1.0, < 13.0.0