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CORS

Configure Cross-Origin Resource Sharing correctly to avoid security issues and debugging pain.

skill openclawclawhub Free
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High Signal

Configure Cross-Origin Resource Sharing correctly to avoid security issues and debugging pain.

⬇ 0 downloads ★ 0 stars Unverified but indexed

Install for OpenClaw

Quick setup
  1. Download the package from Yavira.
  2. Extract the archive and review SKILL.md first.
  3. Import or place the package into your OpenClaw setup.

Requirements

Target platform
OpenClaw
Install method
Manual import
Extraction
Extract archive
Prerequisites
OpenClaw
Primary doc
SKILL.md

Package facts

Download mode
Yavira redirect
Package format
ZIP package
Source platform
Tencent SkillHub
What's included
SKILL.md

Validation

  • Use the Yavira download entry.
  • Review SKILL.md after the package is downloaded.
  • Confirm the extracted package contains the expected setup assets.

Install with your agent

Agent handoff

Hand the extracted package to your coding agent with a concrete install brief instead of figuring it out manually.

  1. Download the package from Yavira.
  2. Extract it into a folder your agent can access.
  3. Paste one of the prompts below and point your agent at the extracted folder.
New install

I downloaded a skill package from Yavira. Read SKILL.md from the extracted folder and install it by following the included instructions. Tell me what you changed and call out any manual steps you could not complete.

Upgrade existing

I downloaded an updated skill package from Yavira. Read SKILL.md from the extracted folder, compare it with my current installation, and upgrade it while preserving any custom configuration unless the package docs explicitly say otherwise. Summarize what changed and any follow-up checks I should run.

Trust & source

Release facts

Source
Tencent SkillHub
Verification
Indexed source record
Version
1.0.0

Documentation

ClawHub primary doc Primary doc: SKILL.md 10 sections Open source page

Preflight Triggers

Any header except: Accept, Accept-Language, Content-Language, Content-Type (with restrictions) Content-Type other than: application/x-www-form-urlencoded, multipart/form-data, text/plain Methods: PUT, DELETE, PATCH, or any custom method ReadableStream in request body Event listeners on XMLHttpRequest.upload One trigger = preflight; simple requests skip OPTIONS entirely

Credentials Mode

Access-Control-Allow-Origin: * incompatible with credentials—must specify exact origin Access-Control-Allow-Credentials: true required for cookies/auth headers Fetch: credentials: 'include'; XHR: withCredentials = true Without credentials mode, cookies not sent even to same origin for cross-origin requests

Wildcard Limitations

* doesn't match subdomains—*.example.com is invalid, not a pattern Can't use * with credentials—specify origin dynamically from request Access-Control-Allow-Headers: * works in most browsers but not all—list explicitly for compatibility Access-Control-Expose-Headers: * same issue—list headers you need to expose

Origin Validation

Check Origin header against allowlist—don't reflect blindly (security risk) Regex matching pitfall: example.com matches evilexample.com—anchor the pattern null origin: sandboxed iframes, file:// URLs—usually reject, never allow as trusted Missing Origin header: same-origin or non-browser client—handle explicitly

Vary Header (Critical)

Always include Vary: Origin when response depends on origin—even if you allow only one Without Vary: CDN/proxy caches response for one origin, serves to others—breaks CORS Add Vary: Access-Control-Request-Headers, Access-Control-Request-Method for preflight caching correctness

Exposed Headers

By default, JS can only read: Cache-Control, Content-Language, Content-Type, Expires, Last-Modified, Pragma Custom headers invisible to JS unless listed in Access-Control-Expose-Headers X-Request-ID, X-RateLimit-*, etc. need explicit exposure—common oversight

Preflight Caching

Access-Control-Max-Age: 86400 caches preflight for 24h—reduces OPTIONS traffic significantly Chrome caps at 2 hours; Firefox at 24 hours—values above are silently reduced Cached per origin + URL + request characteristics—not globally Set to 0 or omit during development—caching hides config changes

Debugging

CORS error in browser = request reached server and came back—check server logs Preflight failure: server must return 2xx with CORS headers on OPTIONS—404/500 = failure Opaque response in fetch: mode: 'no-cors' succeeds but response is empty—usually not what you want Network tab shows CORS errors; Console shows which header is missing

Common Server Mistakes

Only setting CORS headers on main handler, not OPTIONS—preflight fails Setting headers after error response—CORS headers missing on 4xx/5xx breaks error handling Proxy stripping headers—verify headers reach client, not just that server sets them Access-Control-Allow-Origin: "*", "https://example.com"—must be single value, not list

Security

Don't reflect Origin header blindly—validate against allowlist first Private Network Access: Chrome requires Access-Control-Allow-Private-Network: true for localhost access from public web CORS doesn't prevent request from being sent—just blocks response reading; server still processes it Sensitive endpoints: don't rely on CORS alone; use authentication + CSRF tokens

Category context

Identity, auth, scanning, governance, audit, and operational guardrails.

Source: Tencent SkillHub

Largest current source with strong distribution and engagement signals.

Package contents

Included in package
1 Docs
  • SKILL.md Primary doc