GHSA-9cwm-487w-h25w: Mongoose: Reflected XSS via decoded URI in directory listing render

Mongoose is an embedded web server and network library. Prior to 7.22, a remote attacker can send a crafted percent-encoded request path to a deployment using MGENABLEDIRLIST and persuade a user to visit it. The mghttpservedir() and listdir() path in src/http.c places the decoded request URI into the title and h1 elements without HTML entity encoding. The resulting reflected cross-site scripting executes in the Mongoose origin and can expose session data or perform actions as the victim. This issue is fixed in version 7.22.