GHSA-w9f3-qc75-qgx9: PrestaShop has a stored XSS executable in customer service view

PrestaShop has a stored XSS (cross-site scripting, where malicious code is saved in a database and runs when viewed) vulnerability in its back-office customer service section. An attacker without login access can submit a malicious email through the public Contact Us form, which gets stored and then executes when an employee opens the customer thread, potentially allowing the attacker to hijack the employee's session and take over the back-office.