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Fix: Relax resource URI validation to accept base URL (#1517)

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Co-authored-by: Jérémy Ballan <jballan@chapsvision.com>
Co-authored-by: Tarek Mahmoud Sayed <10833894+tarekgh@users.noreply.github.com>
Co-authored-by: Tarek Mahmoud Sayed <tarekms@ntdev.microsoft.com>
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Jérémy 2026-06-01 18:49:23 +02:00 • committed by GitHub
commit 168c37179d
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1 changed files with 122 additions and 16 deletions
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109
tests/ModelContextProtocol.AspNetCore.Tests/OAuth/AuthTests.cs
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@ -768,7 +768,7 @@ public class AuthTests : OAuthTestBase
//
// https://datatracker.ietf.org/doc/html/rfc9728/#section-3.3
//
// CannotAuthenticate_WhenWwwAuthenticateResourceMetadataIsRootPath validates we won't fall back to root in this case.
// CanAuthenticate_WhenWwwAuthenticateResourceMetadataIsRootPath validates that a root-level resource is accepted in this case.
// CanAuthenticate_WithResourceMetadataPathFallbacks validates we will fall back to root when resource_metadata is missing.
Builder.Services.Configure<AuthenticationOptions>(options => options.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme);
Builder.Services.Configure<McpAuthenticationOptions>(McpAuthenticationDefaults.AuthenticationScheme, options =>
@ -807,8 +807,14 @@ public class AuthTests : OAuthTestBase
Assert.Contains("does not match", ex.Message);
}
/// <summary>
/// Verifies that OAuth authentication succeeds when the protected resource metadata URI
/// matches the root server URL, even when the actual MCP endpoint is at a subpath.
/// This tests the flexible URI matching behavior where the resource URI can be less specific
/// than the actual endpoint being accessed.
/// </summary>
[Fact]
public async Task CannotAuthenticate_WhenWwwAuthenticateResourceMetadataIsRootPath()
public async Task CanAuthenticate_WhenWwwAuthenticateResourceMetadataIsRootPath()
{
const string requestedResourcePath = "/mcp/tools";
@ -839,12 +845,99 @@ public class AuthTests : OAuthTestBase
},
}, HttpClient, LoggerFactory);
var ex = await Assert.ThrowsAsync<McpException>(async () =>
await using var client = await McpClient.CreateAsync(
transport, loggerFactory: LoggerFactory, cancellationToken: TestContext.Current.CancellationToken);
}
/// <summary>
/// Verifies that OAuth authentication fails when the protected resource metadata URI
/// does not match the requested MCP server endpoint. This ensures that clients cannot
/// use OAuth tokens intended for one server to access a different server.
/// </summary>
[Fact]
public async Task CannotAuthenticate_WhenResourceMetadataUriDoesNotMatch()
{
const string requestedResourcePath = "/mcp/tools";
const string differentResourceUri = "http://different-server.example.com";
Builder.Services.Configure<McpAuthenticationOptions>(McpAuthenticationDefaults.AuthenticationScheme, options =>
{
await McpClient.CreateAsync(
transport, loggerFactory: LoggerFactory, cancellationToken: TestContext.Current.CancellationToken);
options.ResourceMetadata = new ProtectedResourceMetadata
{
Resource = differentResourceUri,
AuthorizationServers = { OAuthServerUrl },
};
});
await using var app = Builder.Build();
app.MapMcp(requestedResourcePath).RequireAuthorization();
await app.StartAsync(TestContext.Current.CancellationToken);
await using var transport = new HttpClientTransport(new()
{
Endpoint = new Uri($"{McpServerUrl}{requestedResourcePath}"),
OAuth = new()
{
ClientId = "demo-client",
ClientSecret = "demo-secret",
RedirectUri = new Uri("http://localhost:1179/callback"),
AuthorizationRedirectDelegate = HandleAuthorizationUrlAsync,
},
}, HttpClient, LoggerFactory);
// This should fail because the resource URI doesn't match
var ex = await Assert.ThrowsAsync<McpException>(() => McpClient.CreateAsync(
transport, loggerFactory: LoggerFactory, cancellationToken: TestContext.Current.CancellationToken));
Assert.Contains("does not match", ex.Message);
}
/// <summary>
/// Verifies that OAuth authentication fails when the protected resource metadata URI is an
/// unrelated path on the same host as the requested endpoint (e.g. resource=.../service-a vs
/// endpoint .../service-b). This ensures the authority-level fallback only accepts an exact match
/// or an authority-only resource, and not arbitrary sibling paths on the same host.
/// </summary>
[Fact]
public async Task CannotAuthenticate_WhenResourceMetadataResourceIsDifferentPathOnSameAuthority()
{
const string requestedResourcePath = "/service-b";
const string differentResourcePath = "/service-a";
Builder.Services.Configure<McpAuthenticationOptions>(McpAuthenticationDefaults.AuthenticationScheme, options =>
{
options.ResourceMetadata = new ProtectedResourceMetadata
{
Resource = $"{McpServerUrl}{differentResourcePath}",
AuthorizationServers = { OAuthServerUrl },
};
});
await using var app = Builder.Build();
app.MapMcp(requestedResourcePath).RequireAuthorization();
await app.StartAsync(TestContext.Current.CancellationToken);
await using var transport = new HttpClientTransport(new()
{
Endpoint = new Uri($"{McpServerUrl}{requestedResourcePath}"),
OAuth = new()
{
ClientId = "demo-client",
ClientSecret = "demo-secret",
RedirectUri = new Uri("http://localhost:1179/callback"),
AuthorizationRedirectDelegate = HandleAuthorizationUrlAsync,
},
}, HttpClient, LoggerFactory);
// This should fail because the resource URI is a different path on the same host,
// which is neither an exact match nor the authority-only base URL.
var ex = await Assert.ThrowsAsync<McpException>(() => McpClient.CreateAsync(
transport, loggerFactory: LoggerFactory, cancellationToken: TestContext.Current.CancellationToken));
Assert.Contains("does not match", ex.Message);
}
@ -853,7 +946,7 @@ public class AuthTests : OAuthTestBase
{
// This test verifies that automatically derived resource URIs don't have trailing slashes
// and that the client doesn't add them during authentication
// Don't explicitly set Resource - let it be derived from the request
await using var app = await StartMcpServerAsync();
@ -993,10 +1086,10 @@ public class AuthTests : OAuthTestBase
{
// This test verifies that explicitly configured trailing slashes are preserved
const string resourceWithTrailingSlash = "http://localhost:5000/";
// Configure ValidResources to accept the trailing slash version for this test
TestOAuthServer.ValidResources = [resourceWithTrailingSlash, "http://localhost:5000/mcp"];
Builder.Services.Configure<McpAuthenticationOptions>(McpAuthenticationDefaults.AuthenticationScheme, options =>
{
options.ResourceMetadata = new ProtectedResourceMetadata