The Jinja2 XSS vulnerability (CVE-2024-22195) is a cross-site scripting issue that affects all versions prior to 3.1.3 due to the xmlattr filter in Jinja2 when keys containing spaces are used, based on user input, allowing attackers to inject arbitrary HTML attributes into templates and potentially execute untrusted scripts in a user's browser. Developers can check if their project is using a vulnerable version of Jinja2 by looking at the requirements.txt file or running pip list | grep Jinja2 in their project's virtual environment. Upgrading to Jinja2 version 3.1.3 immediately is recommended to address this vulnerability, and tools like Snyk can be used for ongoing vulnerability monitoring and scanning containerized applications with Docker that bundle this vulnerable dependency. Developers should also follow general security best practices such as validating and sanitizing all user inputs, implementing content security policies, and conducting regular security audits.