fix(server): trim OWS from standard MCP headers - #2453
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mattzcarey merged 2 commits intoJul 7, 2026
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🦋 Changeset detectedLatest commit: 12c5c3f The changes in this PR will be included in the next version bump. This PR includes changesets to release 2 packages
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@modelcontextprotocol/client
npm i https://pkg.pr.new/@modelcontextprotocol/client@2453
npm i https://pkg.pr.new/@modelcontextprotocol/codemod@2453
npm i https://pkg.pr.new/@modelcontextprotocol/core@2453
npm i https://pkg.pr.new/@modelcontextprotocol/server@2453
npm i https://pkg.pr.new/@modelcontextprotocol/server-legacy@2453
npm i https://pkg.pr.new/@modelcontextprotocol/express@2453
npm i https://pkg.pr.new/@modelcontextprotocol/fastify@2453
npm i https://pkg.pr.new/@modelcontextprotocol/hono@2453
npm i https://pkg.pr.new/@modelcontextprotocol/node@2453 commit: 38dc1a4 |
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packages/core-internal/src/shared/inboundClassification.ts
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July 7, 2026 12:27
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packages/core-internal/src/shared/inboundClassification.ts
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| // RFC 9110 §5.5: field parsing excludes optional whitespace around a | ||
| // field value. Fetch implementations normally perform this normalization, | ||
| // but transport-neutral callers and some runtimes can expose raw OWS. | ||
| request = { | ||
| ...request, | ||
| ...(request.protocolVersionHeader !== undefined && { | ||
| protocolVersionHeader: stripHttpOws(request.protocolVersionHeader) | ||
| }), | ||
| ...(request.mcpMethodHeader !== undefined && { mcpMethodHeader: stripHttpOws(request.mcpMethodHeader) }), | ||
| ...(request.mcpNameHeader !== undefined && { mcpNameHeader: stripHttpOws(request.mcpNameHeader) }) | ||
| }; |
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nit: seems like something we might want to extract to a normalizeInboundHeaderFields function but seems fine rn
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felixweinberger
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Jul 7, 2026
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Thanks for the CodeQL fix, lgtm
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mattzcarey
enabled auto-merge (squash)
July 7, 2026 13:20
This was referenced Jul 7, 2026
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Fixes #2452.
What changed
Why
@modelcontextprotocol/conformance@0.2.0-alpha.9's ServerAcceptsWhitespaceHeaderValue check fails against @modelcontextprotocol/server@2.0.0-beta.2 on workerd: the valid padded Mcp-Name is compared byte-for-byte with params.name and rejected as HeaderMismatch.
Verification