Executive brief
J2Commerce is an e-commerce extension for Joomla that enables online stores to accept guest checkouts without requiring customer registration. A stored cross-site scripting (XSS) vulnerability in guest checkout allows unauthenticated attackers to inject malicious scripts into billing address fields, which are then stored and executed when viewed by site administrators or other users. This could lead to account takeover, session hijacking, or theft of sensitive customer and order data.
Technical details
The vulnerability is a stored cross-site scripting (XSS) flaw in J2Commerce guest checkout that exploits a filter bypass in Joomla's Input::getArray() method combined with PHP's default variables_order configuration (EGPCS), where cookies override POST parameters in $_REQUEST. Unauthenticated attackers can inject unsanitized HTML and JavaScript into billing address fields (such as billing_first_name) during guest checkout. The malicious payload is stored in the application database without proper sanitization. When administrators or other users view the affected orders or customer data, the stored XSS payload executes in their browsers, potentially allowing session hijacking, credential theft, or administrative account compromise. The vulnerability affects J2Store versions 1.0.0 through 3.3.20, 4.0.0 through 4.0.20, and 4.1.0 through 4.1.5, with no patch information currently available.
Affected products
- j2commerce.com J2Commerce 1.0.0-3.3.20, 4.0.0-4.0.20, 4.1.0-4.1.5
Timeline
- 2026-08-21: disclosed