{"id":"CVE-2024-56412","aliases":["GHSA-q9jv-mm3r-j47r"],"url":"https://o3.security/vulnerability/CVE-2024-56412","summary":"PhpSpreadsheet vulnerable to bypass of the XSS sanitizer using the javascript protocol and special characters","details":"# Bypass XSS sanitizer using the javascript protocol and special characters\n\n**Product**: Phpspreadsheet\n**Version**: version 3.6.0\n**CWE-ID**: CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')\n**CVSS vector v.3.1**: 5.4 (AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N)\n**CVSS vector v.4.0**: 4.8 (AV:N/AC:L/AT:N/PR:L/UI:A/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N)\n**Description**: an attacker can use special characters, so that the library processes the javascript protocol with special characters and generates an HTML link\n**Impact**: executing arbitrary JavaScript code in the browser\n**Vulnerable component**: class `PhpOffice\\PhpSpreadsheet\\Writer\\Html`, method `generateRow`\n**Exploitation conditions**: a user viewing a specially generated Excel file\n**Mitigation**: additional sanitization of special characters in a string\n**Researcher**: Aleksey Solovev (Positive Technologies)\n\n# Research\n\nThe researcher discovered zero-day vulnerability Bypass XSS sanitizer using the javascript protocol and special characters in Phpspreadsheet.\n\nThe following code is written on the server, which translates the XLSX file into a HTML representation and displays it in the response.\n\n*Listing 6. Source code on the server*\n\n```\n<?php\n\nrequire __DIR__ . '/vendor/autoload.php';\n\n$inputFileName = './doc/Book1.xlsx';\n$spreadsheet = \\PhpOffice\\PhpSpreadsheet\\IOFactory::load($inputFileName);\n$writer = new \\PhpOffice\\PhpSpreadsheet\\Writer\\Html($spreadsheet);\nprint($writer->generateHTMLAll());\n```\n\nAn attacker can use special characters so that this library processes the javascript protocol with special characters and generates a HTML link.\nThe Excel file is unpacked and a hyperlink in the file is inserted into the `xl/worksheets/sheet1.xml` file.\n\n![fig11](https://github.com/user-attachments/assets/b9d53f7a-6f36-4853-95f9-8aa22f81eccd)\n\n*Figure 11. Using the javascript protocol with special characters*\n\nSome payloads help bypass the security system and carry out a XSS attack.\n\n*Listing 7. HTML form that demonstrates the exploitation of the XSS vulnerability*\n\n```\njav&#x09;ascript:alert()\njav&#x0D;ascript:alert()\njav&#x0A;ascript:alert()\n```\n\nIt's clear that the javascript protocol with special characters is used. \n\n![fig12](https://github.com/user-attachments/assets/7595e88b-9848-4251-845c-2c2d8032e479)\n\n*Figure 12. Using the javascript protocol with special characters*\n\nDue to the special characters, the execution stream ends up on line 1543, and the link is built in HTML form with the javascript protocol.\n\n<img width=\"373\" alt=\"fig13\" src=\"https://github.com/user-attachments/assets/3ca0c3c6-daa9-4502-ad9e-b803f308fd26\" />\n\n*Figure 13. Executing arbitrary JavaScript code*\n\n# Credit\nThis vulnerability was discovered by **Aleksey Solovev (Positive Technologies)**","published":"2025-01-03T17:20:51.827Z","modified":"2026-08-12T03:51:13.903548405Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Packagist","name":"phpoffice/phpspreadsheet","fixedVersion":"3.7.0"},{"ecosystem":"Packagist","name":"phpoffice/phpspreadsheet","fixedVersion":"1.29.7"},{"ecosystem":"Packagist","name":"phpoffice/phpspreadsheet","fixedVersion":"2.1.6"},{"ecosystem":"Packagist","name":"phpoffice/phpspreadsheet","fixedVersion":"2.3.5"},{"ecosystem":"Packagist","name":"phpoffice/phpexcel","fixedVersion":null}],"fix":{"url":"https://github.com/PHPOffice/PhpSpreadsheet/commit/45052f88e04c735d56457a8ffcdc40b2635a028e","label":"PHPOffice/PhpSpreadsheet@45052f8"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/56xxx/CVE-2024-56412.json"},{"type":"ADVISORY","url":"https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-q9jv-mm3r-j47r"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-56412"},{"type":"FIX","url":"https://github.com/PHPOffice/PhpSpreadsheet/commit/45052f88e04c735d56457a8ffcdc40b2635a028e"},{"type":"PACKAGE","url":"https://github.com/PHPOffice/PhpSpreadsheet"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:13.903548405Z"}}