{"id":"CVE-2026-96640","aliases":[],"title":"Pillow PDF append accepts malformed shared page-tree DAG causing resource exhaustion","titleSource":"GitHub_M","descriptionSource":"GitHub_M","products":[{"vendor":"python-pillow","name":"Pillow","platforms":[],"versions":[{"version":">= 5.1.0, < 13.0.0","status":"affected"}],"source":"GitHub_M","url":"https://www.cve.org/CVERecord?id=CVE-2026-96640"}],"remediation":[],"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13.0.0.","severity":"high","score":8.2,"published":"2026-10-21T21:03:22.785Z","modified":"2026-10-28T01:57:01.680Z","withdrawn":false,"knownExploited":false,"affected":[],"references":["https://github.com/python-pillow/Pillow/security/advisories/GHSA-mrfp-p49p-3hf2","https://github.com/python-pillow/Pillow/pull/10093","https://github.com/python-pillow/Pillow/commit/6f0e7ee1f9c2fe227906f8a4b926e6622b702bc7","https://github.com/python-pillow/Pillow/releases/tag/13.0.0"],"sources":[{"name":"CVE","id":"CVE-2026-96640","modified":"2026-10-28T01:57:01.680Z","url":"https://www.cve.org/CVERecord?id=CVE-2026-96640"}],"assessments":[{"source":"GitHub_M","vector":"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","score":8.2}],"sourceAffected":[],"kev":{"status":"not-listed","checkedAt":"2026-10-28T16:45:33.316Z"},"coverage":[{"source":"NVD","status":"not-checked"},{"source":"GHSA","status":"not-checked"},{"source":"EUVD","status":"not-checked"},{"source":"EPSS","status":"not-checked"}],"evidence":[]}