CVE-2024-45292 in PhpSpreadsheet
Summary
by MITRE • 10/07/2024
PHPSpreadsheet is a pure PHP library for reading and writing spreadsheet files. `\PhpOffice\PhpSpreadsheet\Writer\Html` does not sanitize "javascript:" URLs from hyperlink `href` attributes, resulting in a Cross-Site Scripting vulnerability. This issue has been addressed in release versions 1.29.2, 2.1.1, and 2.3.0. All users are advised to upgrade. There are no known workarounds for this vulnerability.
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Analysis
by VulDB Data Team • 03/08/2025
The vulnerability identified as CVE-2024-45292 affects PHPSpreadsheet, a widely used pure PHP library designed for reading and writing spreadsheet files including xlsx, xls, and csv formats. This library serves as a critical component in numerous web applications that handle data processing and reporting tasks, making its security implications particularly significant for organizations relying on spreadsheet functionality within their software ecosystems.
The technical flaw resides within the `\PhpOffice\PhpSpreadsheet\Writer\Html` class which is responsible for converting spreadsheet data into HTML format. This specific component fails to properly sanitize hyperlink URLs contained in the href attributes of hyperlinks embedded within spreadsheet files. When a spreadsheet containing malicious javascript: URLs is processed and converted to HTML, the vulnerability allows arbitrary JavaScript code to be injected into the resulting HTML output without proper sanitization or encoding.
This cross-site scripting vulnerability operates by leveraging the HTML writer functionality to process spreadsheet files that contain malicious URLs beginning with the javascript: protocol. When such files are rendered in web browsers, the embedded JavaScript code executes within the context of the user's session, potentially leading to session hijacking, data theft, or other malicious activities. The vulnerability represents a classic XSS flaw where untrusted input from spreadsheet hyperlinks is directly embedded into HTML output without proper security validation.
The operational impact of this vulnerability extends beyond simple script execution as it affects any application that utilizes PHPSpreadsheet's HTML export functionality and subsequently displays the generated content to end users. Attackers could craft malicious spreadsheet files containing javascript: URLs in hyperlinks, which when processed by vulnerable applications would execute the malicious code in users' browsers. This creates a significant risk for web applications that allow users to upload and process spreadsheet files, particularly those used in collaborative environments or file sharing systems where untrusted content might be processed.
The vulnerability has been addressed through releases 1.29.2, 2.1.1, and 2.3.0 of PHPSpreadsheet, which implement proper URL sanitization mechanisms to prevent javascript: URLs from being embedded in HTML hyperlink attributes. Security researchers should note that this vulnerability aligns with CWE-79, which describes Cross-Site Scripting vulnerabilities, and follows patterns commonly seen in HTML injection flaws. The remediation approach involves implementing proper input validation and output encoding for URL attributes within the HTML writer component.
Organizations utilizing PHPSpreadsheet should immediately upgrade to the patched versions to mitigate this security risk. The lack of known workarounds means that without upgrading, systems remain vulnerable to exploitation. Security teams should also implement monitoring for any spreadsheet file uploads that might contain suspicious URL patterns and consider additional layers of defense including content security policies and web application firewalls to protect against potential exploitation attempts. This vulnerability demonstrates the importance of proper input sanitization in libraries that process untrusted data and highlights the need for comprehensive security testing of data processing components in web applications.