Multiple cross-site scripting (XSS) vulnerabilities in Serendipity before 2.0.5 allow remote authenticated users to inject arbitrary web script or HTML via a category or directory name.
https://smarterbitbybit.com/cve-2016-9681-serendipity-cms-xss-vulnerability-in-version-2-0-4/
https://github.com/s9y/Serendipity/commit/e2a665e13b7de82a71c9bbb77575d15131b722be