CVE-2024-56410

Cross-Site Scripting (XSS) vulnerability in custom properties

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: the HTML page is generated without clearing custom properties
Impact: executing arbitrary JavaScript code in the browser
Vulnerable component: class PhpOffice\PhpSpreadsheet\Writer\Html, method generateMeta
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 Cross-Site Scripting (XSS) vulnerability in custom properties 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 9. 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->generateHTMLAll());

An attacker can embed a payload in a file property that will result in the execution of arbitrary JavaScript code.
The Excel file is unpacked and a custom property in the file is inserted into the docProps/custom.xml file.

Figure 17. Embedding the payload

After making the changes, a new archive with the xlsx extension was created. At the moment of converting the xlsx file into an HTML representation, a property is obtained that participates in the formation of a string without sanitization.

Figure 18. Getting a custom property

When calling the static generateMeta method, you can see that the key of the custom property is displayed without sanitization.

Figure 19. Getting a custom property

As a result, when viewing the excel file as the HTML representation, arbitrary JavaScript code will be executed.

Figure 20. Executing arbitrary JavaScript code

Credit

This vulnerability was discovered by Aleksey Solovev (Positive Technologies)

Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.

CVE-2024-56410 has a CVSS score of 5.4 (Medium). The vector is network-reachable, low privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.7.0, 1.29.7, 2.1.6, 2.3.5); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2024-56410? CVE-2024-56410 is a medium-severity cross-site scripting (XSS) vulnerability in phpoffice/phpspreadsheet (composer), affecting versions >= 3.0.0, < 3.7.0. It is fixed in 3.7.0, 1.29.7, 2.1.6, 2.3.5. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2024-56410? CVE-2024-56410 has a CVSS score of 5.4 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2024-56410?
   • phpoffice/phpspreadsheet (composer) (versions >= 3.0.0, < 3.7.0)
   • phpoffice/phpexcel (composer) (versions <= 1.8.2)
4. Is there a fix for CVE-2024-56410? Yes. CVE-2024-56410 is fixed in 3.7.0, 1.29.7, 2.1.6, 2.3.5. Upgrade to this version or later.
5. Is CVE-2024-56410 exploitable, and should I be worried? Whether CVE-2024-56410 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2024-56410 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2024-56410?
   • Upgrade phpoffice/phpspreadsheet to 3.7.0 or later
   • Upgrade phpoffice/phpspreadsheet to 1.29.7 or later
   • Upgrade phpoffice/phpspreadsheet to 2.1.6 or later
   • Upgrade phpoffice/phpspreadsheet to 2.3.5 or later