Language: TypeScript
Label: vulnerable
CWE: CWE-352 \u2014 Cross-Site Request Forgery (CSRF)
The web application does not, or can not, sufficiently verify whether a well-formed, valid, consistent request was intentionally provided by the user who submitted the request.

Code:
fastify.register(FastifyCsrfProtection, { getUserInfo(req) {
  return req.session.get('username')
}})