PhpSpreadsheet has a Cross-Site Scripting (XSS) vulnerability in custom properties
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.
<img width="356" alt="fig20" src="https://github.com/user-attachments/assets/a6ed21e3-685c-415c-b2dc-453bc0652bef" />Figure 20. Executing arbitrary JavaScript code
Credit
This vulnerability was discovered by Aleksey Solovev (Positive Technologies)
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Composer package | phpoffice/phpexcel | <= 1.8.2 | no fix |
| Composer package | phpoffice/phpspreadsheet | >= 3.0.0, < 3.7.0, < 1.29.7, >= 2.0.0, < 2.1.6, >= 2.2.0, < 2.3.5 | 3.7.0, 1.29.7, 2.1.6, 2.3.5 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N- Weakness (CWE)
CWE-79- Platform
- Composer
- Package
phpoffice/phpexcel, phpoffice/phpspreadsheet- Disclosed
- 03.01.2025
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-wv23-996v-q229 - CC BY 4.0
Vulnerability history: phpoffice/phpspreadsheet
All published vulnerabilities of this package (Composer package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 31
- First → latest
- 11.2019 07.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 2
- High 17
- Medium 12
Disclosures per year
- 2019: 2
- 2020: 0
- 2021: 1
- 2022: 0
- 2023: 0
- 2024: 9
- 2025: 10
- 2026: 9
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PhpSpreadsheet has a Cross-Site Scripting (XSS) vulnerability in custom properties this entry
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