🚨 CVE-2026-84309
pypdf is a free and open-source pure-python PDF library. Prior to 6.16.0, an attacker can craft a PDF whose cyclic tree structure causes pypdf/generic/_data_structures.py TreeObject.insert_child to follow /Next links indefinitely when a writing code path inserts a child, producing an infinite loop. This issue is fixed in version 6.16.0.
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GitHub
SEC: Detect cycles in TreeObject.insert_child (#3964) · py-pdf/pypdf@c9ba557
A pure-python PDF library capable of splitting, merging, cropping, and transforming the pages of PDF files - SEC: Detect cycles in TreeObject.insert_child (#3964) · py-pdf/pypdf@c9ba557
September 1, 2026 29
