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[Server] Fix CORS preflight behind authorization - #576
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chr-hertel merged 1 commit intoOct 13, 2026
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soyuka
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October 10, 2026 01:56
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🟢 Approval recommended
The focused implementation is consistent with transport behavior and adequately covered by unit tests.
0 open findings
What changed in this PR
Fixes browser CORS preflight requests when MCP authorization and modern request headers are enabled.
Changes:
- Allows unauthenticated
OPTIONSrequests through authorization middleware. - Adds default MCP headers and prefix-based header matching to CORS handling.
- Adds tests and documentation for the updated behavior.
| File | Description |
|---|---|
src/Server/Transport/Http/Middleware/AuthorizationMiddleware.php |
Bypasses token validation for OPTIONS. |
src/Server/Transport/Http/Middleware/CorsMiddleware.php |
Supports MCP headers and header-prefix patterns. |
tests/Unit/Server/Transport/Http/Middleware/AuthorizationMiddlewareTest.php |
Tests unauthenticated preflight handling. |
tests/Unit/Server/Transport/Http/Middleware/CorsMiddlewareTest.php |
Tests default MCP headers and prefix matching. |
docs/run/authorization.md |
Documents middleware ordering and preflight behavior. |
CHANGELOG.md |
Records both CORS fixes. |
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soyuka
approved these changes
Oct 13, 2026
…the MCP request headers
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Browser clients could not reach a server protected by
AuthorizationMiddleware:Authorizationheader, so it got a401and the browser blocked the request.AuthorizationMiddlewarenow letsOPTIONSthrough; the transport answers it without dispatching.CorsMiddlewaredid not allowMcp-Method,Mcp-NameandMcp-Param-*, which every2026-07-28request sends. An$allowedHeadersentry ending in*now matches requested headers by prefix.Follow-up to #566.
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