GHSA-jmpx-686v-c3wx PhpSpreadsheet allows unauthorized Reflected XSS in the constructor of the Downloader class

• Packagist phpoffice/phpspreadsheet: >= 3.0.0, < 3.7.0 → fixed in 3.7.0 • Packagist phpoffice/phpspreadsheet: < 1.29.7 → fixed in 1.29.7 • Packagist phpoffice/phpspreadsheet: >= 2.0.0, < 2.1.6 → fixed in 2.1.6 • Packagist phpoffice/phpspreadsheet: >= 2.2.0, < 2.3.5 → fixed in 2.3.5 • Packagist phpoffice/phpexcel: <= 1.8.2 (no fix yet)

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. *Figure 3. Executing arbitrary JavaScript code* Credit This vulnerability was discovered by Aleksey Solovev (Positive Technologies)