CVE-2026-96640
Pillow PDF append accepts malformed shared page-tree DAG causing resource exhaustion
CVSS Score
0.0
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-400 CWE-407 |
| Vendor | python-pillow |
| Product | pillow |
| Published | Oct 21, 2026 |
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Affected Versions
python-pillow / Pillow
>= 5.1.0, < 13.0.0
References
github.com: https://github.com/python-pillow/Pillow/security/advisories/GHSA-mrfp-p49p-3hf2 github.com: https://github.com/python-pillow/Pillow/pull/10093 github.com: https://github.com/python-pillow/Pillow/commit/6f0e7ee1f9c2fe227906f8a4b926e6622b702bc7 github.com: https://github.com/python-pillow/Pillow/releases/tag/13.0.0