Validate origin header - #771
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Kehrlann merged 2 commits intoFeb 5, 2026
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- Fixes #695 - Does not implement Host header validation yet Signed-off-by: Daniel Garnier-Moiroux <git@garnier.wf>
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February 4, 2026 20:19
Signed-off-by: Daniel Garnier-Moiroux <git@garnier.wf>
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February 4, 2026 20:20
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February 4, 2026 20:23
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...a/io/modelcontextprotocol/server/transport/DefaultServerTransportSecurityValidatorTests.java
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| @Test | ||
| void differentSchemeWithWildcard() { | ||
| var headers = originHeader("https://localhost:3000"); |
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shouldn't the port be 8080 to ensure that it fails because of the schema?
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It's using the the wildcard validator, so the port does not matter:
private final DefaultServerTransportSecurityValidator wildcardValidator =
DefaultServerTransportSecurityValidator
.builder()
.allowedOrigin("http://localhost:*")
.build();
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chemicL
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Feb 10, 2026
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...n/java/io/modelcontextprotocol/server/transport/DefaultServerTransportSecurityValidator.java
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...n/java/io/modelcontextprotocol/server/transport/DefaultServerTransportSecurityValidator.java
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...ain/java/io/modelcontextprotocol/server/transport/HttpServletSseServerTransportProvider.java
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.../main/java/io/modelcontextprotocol/server/transport/HttpServletStatelessServerTransport.java
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| try { | ||
| Map<String, List<String>> headers = extractHeaders(request); | ||
| this.securityValidator.validateHeaders(headers); | ||
| } | ||
| catch (ServerTransportSecurityException e) { | ||
| response.sendError(e.getStatusCode(), e.getMessage()); | ||
| return; | ||
| } |
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This code is duplicated across three implementations, perhaps we can have a centralized static utility for it?
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.../main/java/io/modelcontextprotocol/server/transport/HttpServletStatelessServerTransport.java
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...a/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java
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...a/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java
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...a/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java
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...t/java/io/modelcontextprotocol/server/transport/ServerTransportSecurityIntegrationTests.java
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...rc/main/java/io/modelcontextprotocol/server/transport/WebFluxSseServerTransportProvider.java
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Fixes #695 . Updates conformance tests.
Contents
Add Origin header validation for HTTP-based MCP server transports so servers can restrict which origins can connect (e.g. browser or cross-origin clients).
Introduces new ServerTransportSecurityValidator interface, to validate transport-level security. Default behavior stays permissive: transports use ServerTransportSecurityValidator.NOOP unless a validator is set via the builder.
The provided implementation is DefaultServerTransportSecurityValidator and only validates the Origin header, for now.
New APIs: example usage
Points of interest
Integration tests use the new JUnit 6 @ParameterizedClass API, which is another way of implementation "abstract base classes" for tests.