CVE-2026-87091

A Reflected Cross-Site Scripting (XSS) vulnerability in the Welcart e-Commerce usc-e-shop plugin for WordPress, affecting versions up to 2.12.3, allows an attacker to inject malicious scripts into the page.

The Welcart e-Commerce plugin for WordPress is vulnerable to PHP Object Injection in all versions up to, and including, 2.12.1 via deserialization of untrusted input in the Telecom EDY payment callback (usces_action_acting_transaction). Unauthenticated attackers can store arbitrary 'reserve' key/value pairs as order metadata during a public checkout, then invoke the callback with an attacker-chosen 'option' parameter to select and unserialize that metadata without any provider signature, source-address, transaction-identity or ownership check. A POP chain is present in the TCPDF library bundled with the plugin itself, so no additional plugin or theme is required. This makes it possible for unauthenticated attackers to delete arbitrary files on the server, including wp-config.php, which can lead to remote code execution when an attacker re-runs the WordPress installer against a database they control. Successful exploitation is contingent on an admin printing an invoice to trigger file deletion.

The Welcart e-Commerce plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'custom_order' parameter in all versions up to, and including, 2.12.1 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The injected payload is delivered via the guest checkout form, requiring no authentication, and executes when an administrator views the affected order in the WordPress admin panel.

The Welcart e-Commerce WordPress plugin before 2.12.1 does not regenerate the session identifier on authentication and sets the session identifier from a user-supplied request parameter, allowing an unauthenticated attacker to fixate a shop member's session and take over their customer account after the victim logs in through an attacker-crafted request.

Unauthenticated Cross Site Scripting (XSS) in Welcart e-Commerce versions up to 2.11.31. An attacker can inject malicious script without authentication.

The Welcart e-Commerce WordPress plugin before 2.11.33 does not verify the authenticity of its convenience-store / bank-transfer settlement callback: an unauthenticated request can flip an order from unpaid to settled purely from an order number and a status flag, with no signature, amount, or origin check. Because these are pay-later methods, an attacker can mark their own unpaid order as settled and obtain fulfilment without paying.

The Welcart e-Commerce WordPress plugin before 2.11.34 does not sanitise or escape a product field before outputting it on the product pages, allowing users with the Author role and above to inject arbitrary web scripts that execute in the browser of any visitor viewing the product page.

Welcart e-Commerce versions up to 2.11.28 have an issue with unauthenticated access that can lead to broken access control.

The Welcart e-Commerce plugin for WordPress is vulnerable to unauthorized data access due to a missing capability check on the 'usces_export' action in all versions up to and including 2.11.24. This allows unauthenticated attackers to access configured payment credentials (e.g., PayPal API secret), business contact details, mail templates, and other operational settings.

The Welcart e-Commerce (usc-e-shop) plugin has a missing authorization vulnerability, allowing exploitation of incorrectly configured access control security levels. This issue affects versions up to and including 2.11.24.