GHSA-x88g-h956-m5xg PhpSpreadsheet allows unauthorized Reflected XSS in `Convert-Online.php` file

• 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 `Convert-Online.php` file 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/Engineering/Convert-Online.php` script, an attacker can perform a XSS-type attack Impact: executing arbitrary JavaScript code in the browser Vulnerable component: the `/vendor/phpoffice/phpspreadsheet/samples/Engineering/Convert-Online.php` file Exploitation conditions: an unauthorized user Mitigation: sanitization of the quantity variable Researcher: Aleksey Solovev (Positive Technologies) Research The researcher discovered zero-day vulnerability Unauthorized Reflected Cross-Site Scripting (XSS) (in `Convert-Online.php` file) in Phpspreadsheet. There is no sanitization in the `/vendor/phpoffice/phpspreadsheet/samples/Engineering/Convert-Online.php` file, which leads to the possibility of a XSS attack. *Figure 4. The message with the quantity parameter is displayed without sanitization* The following figure shows a POST HTTP-request and a response to the server with the variable quantity, which is displayed in the response from the server without sanitization. *Figure 5. In the server's response , the quantity variable is displayed without sanitization* An attacker can prepare a special HTML form that will be automatically sent to the vulnerable scenario. *Listing 3. HTML form that demonstrates the exploitation of the XSS vulnerability* ``` history.pushState('', '', '/'); document.forms[0].submit(); ``` After the user visits the attacker's resource, the form will be sent to the vulnerable scenario, which will lead to the execution of arbitrary code in the client's browser. *Figure 6. Executing arbitrary JavaScript code* Credit This vulnerability was discovered by Aleksey Solovev (Positive Technologies)