PhpSpreadsheet allows bypass XSS sanitizer using the javascript protocol and special characters
Date: 2025-01
Affected: composer/phpoffice/phpexcel, composer/phpoffice/phpspreadsheet, composer/phpoffice/phpspreadsheet
Attack vector: xss
Category: vulnerability-disclosure
Severity: Medium
CVE: CVE-2024-56410
CVE-2024-56411
CVE-2024-56412
CWE: CWE-79
CVSS: 5.4 (CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N)

# Bypass XSS sanitizer using the javascript protocol and special characters **Product**: Phpspreadsheet **Version**: version 3.6.0 **CWE-ID**: CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') **CVSS vector v.3.1**: 5.4 (AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A: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) **Description**: an attacker can use special characters, so that the library processes the javascript protocol with special characters and generates an HTML link **Impact**: executing arbitrary JavaScript code in the browser **Vulnerable component**: class `PhpOffice\PhpSpreadsheet\Writer\Html`, method `generateRow` **Exploitation conditions**: a user viewing a specially generated Excel file **Mitigation**: additional sanitization of special characters in a string **Researcher**: Aleksey Solovev (Positive Technologies) # Research The researcher discovered zero-day vulnerability Bypass XSS sanitizer using the javascript protocol and special characters in Phpspreadsheet. The following code is written on the server, which translates the XLSX file into a HTML representation and displays it in the response. *Listing 6. Source code on the server* ``` <?php require __DIR__ . '/vendor/autoload.php'; $inputFileName = './doc/Book1.xlsx'; $spreadsheet = \PhpOffice\PhpSpreadsheet\IOFactory::load($inputFileName); $writer = new \PhpOffice\PhpSpreadsheet\Writer\Html($spreadsheet); print($writer->generateH


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