CVE-2026-96640Published

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

Exact source revision recorded 28 Oct 2026 02:51:34 UTC. It does not establish the source's current position. Latest evidence.

Recorded JSON

cve-program · CVE-2026-96640

Published

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.

Source published: 21 Oct 2026 21:03:22 UTC
Source modified: 28 Oct 2026 01:57:01 UTC
Observed here: 28 Oct 2026 02:51:34 UTC
Source terms: CVE Program Terms of Use

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CVSS 4.0 · 8.2 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