Strapi is an open source headless content management system. Strapi versions prior to 5.20.0 contain a CORS misconfiguration vulnerability in default installations. By default, Strapi reflects the value of the Origin header back in the Access-Control-Allow-Origin response header without proper validation or whitelisting. This allows an attacker-controlled site to send credentialed requests to the Strapi backend. An attacker can exploit this by hosting a malicious site on a different origin (e.g., different port) and sending requests with credentials to the Strapi API. The vulnerability is fixed in version 5.20.0. No known workarounds exist.