{
  "port": 6004,
  "protocol": "tcp",
  "service": "X11 display :4",
  "oneLiner": "X display :4 — another slot in the 6000-6063 X Window System range.",
  "whatItIs": "IANA covers 6004 under the same `x11` assignment as 6000-6063, making it display :4. Hosts reach it when they run several X servers at once: multi-seat desktops, CI runners spawning Xvfb per job, or a VNC host on its fifth display (paired with RFB 5904). Authorization is still xhost or MIT-MAGIC-COOKIE-1, and the protocol is still cleartext.",
  "exposure": {
    "verdict": "never",
    "note": "A reachable X display hands an attacker the screen contents and the keyboard. Start the server with `-nolisten tcp` and use SSH X forwarding for remote access."
  },
  "checkCommand": "xdpyinfo -display TARGET:4",
  "links": [
    {
      "title": "X.Org — Xserver(1) manual page",
      "url": "https://xorg.freedesktop.org/archive/current/doc/man/man1/Xserver.1.xhtml",
      "kind": "official-docs"
    },
    {
      "title": "IANA port registry — 6000-6063 (x11)",
      "url": "https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=x11",
      "kind": "iana"
    },
    {
      "title": "X.Org Server source repository (xorg/xserver)",
      "url": "https://gitlab.freedesktop.org/xorg/xserver",
      "kind": "official-docs"
    }
  ]
}