CVE-2026-81568: fallo de gravedad alta en j2commerce.com J2Store extension for Joomla

Joomla Extension - j2commerce.com - Arbitrary file read via `task=download` in J2Store 1.0.0-3.3.2, 4.0.0-4.0.22, 4.1.0-4.1.7 - `J2StoreModelOrderdownloads::getFilePath()` built the on-disk path to a purchased digital download by concatenating the configured attachment folder with the product file's stored `product_file_save_name`, using only `JPath::clean()` (which normalises separators but does not resolve or reject `..` segments) and a plain `JFile::exists()` check — never confirming the resolved path stayed inside the configured attachment folder. If a product file's `product_file_save_name` ever contained a `../` traversal segment — most plausibly via the CSRF-forgeable admin product-file save actions described in Issue 1, but equally by any future integration or bug that writes that field — any customer holding a valid download `token`/`pid` pair for that product file could have the traversal resolve to a path outside the attachment folder and download any file readable by the web server (e.g. `configuration.php`).