CVE-2024-56408: PhpSpreadsheet allows unauthorized Reflected XSS in `Convert-Online.php` file

Unauthorized Reflected XSS in <code>Convert-Online.php</code> 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