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DefaultSseMessageEndpointValidator allows same-origin message endpoints

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Signed-off-by: Daniel Garnier-Moiroux <git@garnier.wf>
This commit is contained in:
Daniel Garnier-Moiroux 2026-05-04 10:16:45 +02:00 • committed by Daniel Garnier-Moiroux
commit bf30e21f0d
1 changed files with 25 additions and 21 deletions
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21
mcp-core/src/test/java/io/modelcontextprotocol/client/transport/DefaultSseMessageEndpointValidatorTests.java
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@ -25,7 +25,7 @@ class DefaultSseMessageEndpointValidatorTests {
private final DefaultSseMessageEndpointValidator validator = new DefaultSseMessageEndpointValidator();
@ParameterizedTest
@ValueSource(strings = { "/messages", "messages?session=abc", "/" })
@ValueSource(strings = { "/messages", "messages?session=abc", "/", "https://mcp.example.com/messages" })
void valid(String endpoint) {
assertThatCode(() -> validator.validate(SSE_URI, endpoint)).doesNotThrowAnyException();
}
@ -41,20 +41,20 @@ class DefaultSseMessageEndpointValidatorTests {
@ParameterizedTest
@ValueSource(strings = { "/foo/../bar", "/foo/./bar", "../bar", "./bar", "/foo/%2E%2E/bar", "/foo/%2e/bar" })
void invalidPathTraversal(String endpoint) {
assertThatThrownBy(() -> validator.validate(SSE_URI, endpoint)).hasMessageContaining("path-traversal")
assertThatThrownBy(() -> validator.validate(SSE_URI, endpoint))
.hasMessageContaining("must not contain path-traversal segments")
.asInstanceOf(type(InvalidSseMessageEndpointException.class))
.extracting(InvalidSseMessageEndpointException::getMessageEndpoint)
.isEqualTo(endpoint);
}
@ParameterizedTest
@ValueSource(strings = { "https://mcp.example.com/messages", "https://127.0.0.1/messages",
"https://mcp.example.com:8443/messages", "http://localhost:1234/messages", "file:///etc/passwd",
"gopher://mcp.example.com/_test" })
@ValueSource(strings = { "https://127.0.0.1/messages", "https://mcp.example.com:8443/messages",
"http://localhost:1234/messages", "file:///etc/passwd", "gopher://mcp.example.com/_test" })
void invalidAbsoluteUris(String endpoint) {
// Even an absolute URI on the same origin must be rejected: the contract
// is that the messageEndpoint is a path-only relative reference.
assertThatThrownBy(() -> validator.validate(SSE_URI, endpoint)).hasMessageContaining("must be a relative path")
// Absolute URIs must be same-origin.
assertThatThrownBy(() -> validator.validate(SSE_URI, endpoint))
.hasMessageContaining("must be a relative path or a same-origin URI")
.asInstanceOf(type(InvalidSseMessageEndpointException.class))
.extracting(InvalidSseMessageEndpointException::getMessageEndpoint)
.isEqualTo(endpoint);
@ -62,11 +62,12 @@ class DefaultSseMessageEndpointValidatorTests {
}
@ParameterizedTest
@ValueSource(strings = { "//example/messages", "//user:secret@example/messages" })
@ValueSource(strings = { "//example/messages", "//user:secret@example/messages", "//mcp.example.com/messages" })
void invalidNetworkReference(String endpoint) {
// `//host/...` introduces an authority and is therefore not a pure path.
// It is missing a scheme, so it fails same-origin check.
assertThatThrownBy(() -> validator.validate(SSE_URI, endpoint))
.hasMessageContaining("must not contain an authority")
.hasMessageContaining("must be a relative path or a same-origin URI")
.asInstanceOf(type(InvalidSseMessageEndpointException.class))
.extracting(InvalidSseMessageEndpointException::getMessageEndpoint)
.isEqualTo(endpoint);