CVE-2024-56365

# Unauthorized Reflected XSS in the constructor of the `Downloader` class **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**: 8.2 (AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:H/A:N) **CVSS vector v.4.0**: 8.3 (AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:N/SC:L/SI:H/SA:L) **Description**: using the `/vendor/phpoffice/phpspreadsheet/samples/download.php` script, an attacker can perform a XSS-type attack **Impact**: execution of arbitrary JavaScript code in the browser **Vulnerable component**: the constructor of the `Downloader` class **Exploitation conditions**: an unauthorized user **Mitigation**: sanitization of the `name` and `type` variables **Researcher**: Aleksey Solovev (Positive Technologies) # Research The researcher discovered zero-day vulnerability Unauthorized Reflected Cross-Site Scripting (XSS) (in the constructor of the `Downloader` class) in Phpspreadsheet. The latest version (3.6.0) of the `phpoffice/phpspreadsheet` library was installed. The installation was carried out with the inclusion of examples. *Listing 1. Installing the `phpoffice/phpspreadsheet` library* ``` $ composer require phpoffice/phpspreadsheet --prefer-source ``` The `./vendor/phpoffice/phpspreadsheet/samples/download.php` file processes the GET parameters `name` and `type`.  *Figure 1. The `./vendor/phpoffice/phpspreadsheet/samples/download.php` file accepts GET parameters.* Consider the constructor of the `Downloader` class, where GET parameters are passed. Error is displayed without sanitization using GET parameters transmitted from the user.  *Figure 2. Error is displayed without sanitization* When clicking on the following link, arbitrary JavaScript code will be executed. *Listing 2.* ``` https://192.***.***.***/vendor/phpoffice/phpspreadsheet/samples/download.php?name=%3Cimg%20src=1%20onerror=alert()%3E&type=1 ``` Demonstration of the execution of arbitrary JavaScript code. <img width="537" alt="fig3" src="https://github.com/user-attachments/assets/745d6e21-396f-4357-8ff8-e856adf15fee" /> *Figure 3. Executing arbitrary JavaScript code* # Credit This vulnerability was discovered by **Aleksey Solovev (Positive Technologies)**