Individual skill

websocket-security

Securing the WebSocket upgrade and the frames after it: Origin validation against Cross-Site WebSocket Hijacking, authenticating the handshake rather than the first message, the ticket pattern for browsers that cannot set headers, per-frame authorization, and resource limits on a connection that stays open. Use when generating a WebSocket, Socket.IO, SignalR, or Phoenix Channels server, wiring real-time messaging, presence, or collaborative editing, or reviewing a /ws endpoint.

skills/websocket-security/SKILL.md

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Last checked: Nov 6, 2026

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Repository stars (not skill ratings): 23
Repository last updated: Aug 14, 2026
License: MIT

Observed agent integration: No specific integration evidence. Standard SKILL.md installation does not imply verified compatibility.

claude-skills Repository topic
llm Repository topic
security Repository topic
skills Repository topic
writing Derived category

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SKILL.mdcore · 9,051 bytes
SKILL.mdcore · 9,051 bytes
SKILL.mdcore · 9,051 bytes
SKILL.mdcore · 9,051 bytes
SKILL.mdcore · 9,051 bytes
references/limits-and-handshake.mddoc · 6,048 bytes
references/verifying-findings.mddoc · 3,655 bytes
rules/websocket_hardening.jsonasset · 3,521 bytes
tests/corpus.jsonasset · 5,626 bytes

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# WebSocket Security

## Rules (for AI agents)

### ALWAYS
- Validate the **`Origin` header** on the upgrade handshake against an allowlist, and
  understand precisely what that buys: the browser sets `Origin` and script cannot
  forge it, so the check stops **Cross-Site WebSocket Hijacking** — a page on
  `attacker.com` opening `wss://api.example.com/ws` and inheriting the user's cookies.
  It buys nothing against a non-browser client, which sets any header it likes. Origin
  is a CSRF control, not authentication. The same-origin policy and CORS preflight do
  not apply to the upgrade at all, which is why this check must be written by hand.
- Authenticate the **handshake**, not the first frame. Once the upgrade completes the
  connection exists, has consumed the user's cookie context, and is already a resource