{"id":"CVE-2026-96640","state":"PUBLISHED","title":"Pillow PDF append accepts malformed shared page-tree DAG causing resource exhaustion","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.","publishedAt":"2026-10-21T21:03:22.785Z","updatedAt":"2026-10-28T01:57:01.680Z","severity":{"score":8.2,"label":"High","version":"4.0","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","source":"GitHub_M"},"assigner":"GitHub_M","products":["python-pillow Pillow"],"affected":[{"vendor":"python-pillow","product":"Pillow","versions":[{"version":">= 5.1.0, < 13.0.0","status":"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"],"weaknesses":["CWE-400","CWE-407"],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/96xxx/CVE-2026-96640.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-96640","state":"PUBLISHED","datePublished":"2026-10-21T21:03:22.785Z","dateUpdated":"2026-10-28T01:57:01.680Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-09-23T14:35:50.130Z"},"containers":{"cna":{"title":"Pillow PDF append accepts malformed shared page-tree DAG causing resource exhaustion","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"python-pillow","product":"Pillow","versions":[{"version":">= 5.1.0, < 13.0.0","status":"affected"}]}],"references":[{"url":"https://github.com/python-pillow/Pillow/security/advisories/GHSA-mrfp-p49p-3hf2","name":"https://github.com/python-pillow/Pillow/security/advisories/GHSA-mrfp-p49p-3hf2","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/python-pillow/Pillow/pull/10093","name":"https://github.com/python-pillow/Pillow/pull/10093","tags":["x_refsource_MISC"]},{"url":"https://github.com/python-pillow/Pillow/commit/6f0e7ee1f9c2fe227906f8a4b926e6622b702bc7","name":"https://github.com/python-pillow/Pillow/commit/6f0e7ee1f9c2fe227906f8a4b926e6622b702bc7","tags":["x_refsource_MISC"]},{"url":"https://github.com/python-pillow/Pillow/releases/tag/13.0.0","name":"https://github.com/python-pillow/Pillow/releases/tag/13.0.0","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"HIGH","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":8.2,"baseSeverity":"HIGH","vectorString":"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","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-400","lang":"en","description":"CWE-400: Uncontrolled Resource Consumption","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-407","lang":"en","description":"CWE-407: Inefficient Algorithmic Complexity","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-10-21T21:03:22.785Z"},"source":{"advisory":"GHSA-mrfp-p49p-3hf2","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/python-pillow/Pillow/security/advisories/GHSA-mrfp-p49p-3hf2","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-28T01:56:31.079893Z","id":"CVE-2026-96640","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-28T01:57:01.680Z"}}]}}}