High 8.2Published Oct 21, 2026

CVE-2026-96640Pillow PDF append accepts malformed shared page-tree DAG causing resource exhaustion

Updated under an hour ago (Oct 27, 2026, 10:10 PM ET)

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It affects python-pillow Pillow and 1 other product. Add what you run to find out whether that includes you.

EPSS puts the chance of exploitation in the next 30 days at 0.52%, higher than 44% of scored CVEs.

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Every CVE for python-pillow Pillow

Exploited in the last 30 days

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: 8.2 HIGH (v4.0, CNA)CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weakness (CWE): CWE-400, CWE-407
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): 0.52% (percentile 44)
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Oct 27, 2026
First seen by InfoSec Signals: Oct 21, 2026

Affected products

Affected products

python-pillow Pillow python_pillow:pillow (from the name)	from 5.1.0, < 13.0.0	CNA record
python pillow python:pillow	from 5.1.0 before 13.0.0	NVD

References

References

https://github.com/python-pillow/Pillow/security/advisories/GHSA-mrfp-p49p-3hf2	x-refsource-confirm, vendor-advisory
https://github.com/python-pillow/Pillow/pull/10093	x-refsource-misc, issue-tracking
https://github.com/python-pillow/Pillow/commit/6f0e7ee1f9c2fe227906f8a4b926e6622b702bc7	x-refsource-misc, patch
https://github.com/python-pillow/Pillow/releases/tag/13.0.0	x-refsource-misc, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.