Naked: kid traversal

One bug: the verifier reads its HMAC key from a file named by the token header’s kid, joined onto a keys directory with no sanitisation. The legit key file (ratauth.key) is on disk but you cannot read it. Point kid at a file whose contents you already know — e.g. an empty one — sign the token with that known key, and reach /naked/kid/admin as admin.

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{
  "alg": "HS256",
  "typ": "JWT",
  "kid": "ratauth.key"
}

{
  "sub": "demo",
  "uid": 2,
  "role": "user"
}

Present your forged token as the pp_kid cookie, or as ?token=<jwt>.

More hands-on practice → labs.hackxpert.com