Vulnerability 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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Python | Pillow | >= 5.1.0, < 13.0.0 |
Related Weaknesses (CWE)
References
- https://github.com/python-pillow/Pillow/commit/6f0e7ee1f9c2fe227906f8a4b926e6622Patch
- https://github.com/python-pillow/Pillow/pull/10093Issue Tracking
- https://github.com/python-pillow/Pillow/releases/tag/13.0.0Release Notes
- https://github.com/python-pillow/Pillow/security/advisories/GHSA-mrfp-p49p-3hf2Vendor Advisory
- https://github.com/python-pillow/Pillow/security/advisories/GHSA-mrfp-p49p-3hf2Vendor Advisory
FAQ
What is CVE-2026-96640?
CVE-2026-96640 is a vulnerability with a CVSS score of 7.5 (HIGH). 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....
How severe is CVE-2026-96640?
CVE-2026-96640 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-96640?
Check the references section above for vendor advisories and patch information. Affected products include: Python Pillow.