{"id":"BIT-pillow-2026-96640","summary":"Pillow PDF append accepts malformed shared page-tree DAG causing resource exhaustion","details":"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.","aliases":["CVE-2026-96640","GHSA-mrfp-p49p-3hf2"],"modified":"2026-10-29T10:55:39.916451864Z","published":"2026-10-29T08:58:15.618Z","database_specific":{"severity":"High","cpes":["cpe:2.3:a:python:pillow:*:*:*:*:*:python:*:*"]},"references":[{"type":"FIX","url":"https://github.com/python-pillow/Pillow/commit/6f0e7ee1f9c2fe227906f8a4b926e6622b702bc7"},{"type":"REPORT","url":"https://github.com/python-pillow/Pillow/pull/10093"},{"type":"ARTICLE","url":"https://github.com/python-pillow/Pillow/releases/tag/13.0.0"},{"type":"ADVISORY","url":"https://github.com/python-pillow/Pillow/security/advisories/GHSA-mrfp-p49p-3hf2"},{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-96640"}],"affected":[{"package":{"name":"pillow","ecosystem":"Bitnami","purl":"pkg:bitnami/pillow"},"ranges":[{"type":"SEMVER","events":[{"introduced":"5.1.0"},{"fixed":"13.0.0"}]}],"database_specific":{"source":"https://github.com/bitnami/vulndb/tree/main/data/pillow/BIT-pillow-2026-96640.json"},"severity":[{"type":"CVSS_V4","score":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"}]}],"schema_version":"1.9.2"}