diff --git a/docs/servers/auth/oauth-proxy.mdx b/docs/servers/auth/oauth-proxy.mdx
index 03727ec87..c8bf9516b 100644
--- a/docs/servers/auth/oauth-proxy.mdx
+++ b/docs/servers/auth/oauth-proxy.mdx
@@ -342,6 +342,26 @@ auth = OAuthProxy(..., client_storage=MemoryStore())
+
+ Sets an explicit domain for the signed cookies used by FastMCP's consent flow. By default, FastMCP uses `__Host-` cookies on HTTPS, which browsers restrict to the exact host.
+
+ Set this only when a hosting layer, such as Azure Functions, adds a `Domain` attribute to response cookies. The value must exactly match the hostname in `base_url`; FastMCP rejects parent domains. Configuring it uses `__Secure-` cookies and preserves signing, `Secure`, `HttpOnly`, and `SameSite=Lax`.
+
+ ```python
+ from fastmcp.server.auth.providers.azure import AzureProvider
+
+ auth = AzureProvider(
+ ...,
+ base_url="https://my-app.azurewebsites.net",
+ consent_cookie_domain="my-app.azurewebsites.net",
+ )
+ ```
+
+
+ Prefer the host-only default. A domain cookie is also sent to child subdomains, so only enable this when those hosts are trusted and the deployment platform makes `__Host-` cookies unusable.
+
+
+
Content Security Policy for the consent page.
diff --git a/docs/servers/auth/oidc-proxy.mdx b/docs/servers/auth/oidc-proxy.mdx
index be4bcb22d..a1b62f52e 100644
--- a/docs/servers/auth/oidc-proxy.mdx
+++ b/docs/servers/auth/oidc-proxy.mdx
@@ -209,6 +209,10 @@ auth = OIDCProxy(
Consent screen behavior for authorization requests. Accepts `True` (default; always prompt — strongest protection), `"remember"` (silent consent on return visits via signed cookie, gated by `Sec-Fetch-Site` to block AS-in-the-middle attacks), `"external"` (same authorization path as `False`, but the warning is suppressed because the operator asserts that equivalent protections are enforced externally), or `False` (disable entirely; local/testing only). See the [OAuthProxy documentation](/servers/auth/oauth-proxy) for full details on each mode and the security trade-offs.
+
+ Explicit domain for consent cookies. By default, FastMCP uses host-only `__Host-` cookies on HTTPS. Set this only for hosting layers that add a `Domain` attribute; the value must exactly match the hostname in `base_url`. See the [OAuthProxy documentation](/servers/auth/oauth-proxy) for the security trade-off.
+
+
Content Security Policy for the consent page.
diff --git a/docs/v2/servers/auth/oauth-proxy.mdx b/docs/v2/servers/auth/oauth-proxy.mdx
index 678c396b5..5daef663e 100644
--- a/docs/v2/servers/auth/oauth-proxy.mdx
+++ b/docs/v2/servers/auth/oauth-proxy.mdx
@@ -323,6 +323,26 @@ auth = OAuthProxy(..., client_storage=MemoryStore())
+
+ Sets an explicit domain for the signed cookies used by FastMCP's consent flow. By default, FastMCP uses `__Host-` cookies on HTTPS, which browsers restrict to the exact host.
+
+ Set this only when a hosting layer, such as Azure Functions, adds a `Domain` attribute to response cookies. The value must exactly match the hostname in `base_url`; FastMCP rejects parent domains. Configuring it uses `__Secure-` cookies and preserves signing, `Secure`, `HttpOnly`, and `SameSite=Lax`.
+
+ ```python
+ from fastmcp.server.auth.providers.azure import AzureProvider
+
+ auth = AzureProvider(
+ ...,
+ base_url="https://my-app.azurewebsites.net",
+ consent_cookie_domain="my-app.azurewebsites.net",
+ )
+ ```
+
+
+ Prefer the host-only default. A domain cookie is also sent to child subdomains, so only enable this when those hosts are trusted and the deployment platform makes `__Host-` cookies unusable.
+
+
+
Content Security Policy for the consent page.
diff --git a/docs/v2/servers/auth/oidc-proxy.mdx b/docs/v2/servers/auth/oidc-proxy.mdx
index a7988995e..c90efc171 100644
--- a/docs/v2/servers/auth/oidc-proxy.mdx
+++ b/docs/v2/servers/auth/oidc-proxy.mdx
@@ -202,6 +202,10 @@ auth = OIDCProxy(
Consent screen behavior for authorization requests. Accepts `True` (default; always prompt — strongest protection), `"remember"` (silent consent on return visits via signed cookie, gated by `Sec-Fetch-Site` to block AS-in-the-middle attacks), `"external"` (same authorization path as `False`, but the warning is suppressed because the operator asserts that equivalent protections are enforced externally), or `False` (disable entirely; local/testing only). See the [OAuthProxy documentation](/v2/servers/auth/oauth-proxy) for full details on each mode and the security trade-offs.
+
+ Explicit domain for consent cookies. By default, FastMCP uses host-only `__Host-` cookies on HTTPS. Set this only for hosting layers that add a `Domain` attribute; the value must exactly match the hostname in `base_url`. See the [OAuthProxy documentation](/servers/auth/oauth-proxy) for the security trade-off.
+
+
Content Security Policy for the consent page.
diff --git a/docs/v3/servers/auth/oauth-proxy.mdx b/docs/v3/servers/auth/oauth-proxy.mdx
index 79ba7bf09..d7227b961 100644
--- a/docs/v3/servers/auth/oauth-proxy.mdx
+++ b/docs/v3/servers/auth/oauth-proxy.mdx
@@ -337,6 +337,26 @@ auth = OAuthProxy(..., client_storage=MemoryStore())
+
+ Sets an explicit domain for the signed cookies used by FastMCP's consent flow. By default, FastMCP uses `__Host-` cookies on HTTPS, which browsers restrict to the exact host.
+
+ Set this only when a hosting layer, such as Azure Functions, adds a `Domain` attribute to response cookies. The value must exactly match the hostname in `base_url`; FastMCP rejects parent domains. Configuring it uses `__Secure-` cookies and preserves signing, `Secure`, `HttpOnly`, and `SameSite=Lax`.
+
+ ```python
+ from fastmcp.server.auth.providers.azure import AzureProvider
+
+ auth = AzureProvider(
+ ...,
+ base_url="https://my-app.azurewebsites.net",
+ consent_cookie_domain="my-app.azurewebsites.net",
+ )
+ ```
+
+
+ Prefer the host-only default. A domain cookie is also sent to child subdomains, so only enable this when those hosts are trusted and the deployment platform makes `__Host-` cookies unusable.
+
+
+
Content Security Policy for the consent page.
diff --git a/docs/v3/servers/auth/oidc-proxy.mdx b/docs/v3/servers/auth/oidc-proxy.mdx
index 81ca677a2..8993b5e3b 100644
--- a/docs/v3/servers/auth/oidc-proxy.mdx
+++ b/docs/v3/servers/auth/oidc-proxy.mdx
@@ -202,6 +202,10 @@ auth = OIDCProxy(
Consent screen behavior for authorization requests. Accepts `True` (default; always prompt — strongest protection), `"remember"` (silent consent on return visits via signed cookie, gated by `Sec-Fetch-Site` to block AS-in-the-middle attacks), `"external"` (same authorization path as `False`, but the warning is suppressed because the operator asserts that equivalent protections are enforced externally), or `False` (disable entirely; local/testing only). See the [OAuthProxy documentation](/servers/auth/oauth-proxy) for full details on each mode and the security trade-offs.
+
+ Explicit domain for consent cookies. By default, FastMCP uses host-only `__Host-` cookies on HTTPS. Set this only for hosting layers that add a `Domain` attribute; the value must exactly match the hostname in `base_url`. See the [OAuthProxy documentation](/servers/auth/oauth-proxy) for the security trade-off.
+
+
Content Security Policy for the consent page.
diff --git a/fastmcp_slim/fastmcp/server/auth/oauth_proxy/consent.py b/fastmcp_slim/fastmcp/server/auth/oauth_proxy/consent.py
index 5eda1d70d..21b37414a 100644
--- a/fastmcp_slim/fastmcp/server/auth/oauth_proxy/consent.py
+++ b/fastmcp_slim/fastmcp/server/auth/oauth_proxy/consent.py
@@ -76,6 +76,8 @@ class ConsentMixin:
def _cookie_name(self: OAuthProxy, base_name: str) -> str:
"""Return secure cookie name for HTTPS, fallback for HTTP development."""
if self._is_https:
+ if self._consent_cookie_domain is not None:
+ return f"__Secure-{base_name}"
return f"__Host-{base_name}"
return f"__{base_name}"
@@ -129,9 +131,8 @@ class ConsentMixin:
"""Decode and verify a signed base64-encoded JSON list from cookie. Returns [] if missing/invalid."""
secure_name = self._cookie_name(base_name)
raw = request.cookies.get(secure_name)
- # Only fall back to the non-__Host- name over plain HTTP. On HTTPS,
- # __Host- enforces host-only scope; accepting the weaker name would
- # let a sibling-subdomain attacker inject a domain-scoped cookie.
+ # Only fall back to the unprefixed development name over plain HTTP.
+ # On HTTPS, accept exactly the prefix selected by the configured policy.
if not raw and not self._is_https:
raw = request.cookies.get(f"__{base_name}")
if not raw:
@@ -177,6 +178,7 @@ class ConsentMixin:
httponly=True,
samesite="lax",
path="/",
+ domain=self._consent_cookie_domain,
)
def _read_consent_bindings(self: OAuthProxy, request: Request) -> dict[str, str]:
@@ -186,9 +188,8 @@ class ConsentMixin:
"""
cookie_name = self._cookie_name("MCP_CONSENT_BINDING")
raw = request.cookies.get(cookie_name)
- # Only fall back to the non-__Host- name over plain HTTP. On HTTPS,
- # __Host- enforces host-only scope; accepting the weaker name would
- # bypass that guarantee.
+ # Only fall back to the unprefixed development name over plain HTTP.
+ # On HTTPS, accept exactly the prefix selected by the configured policy.
if not raw and not self._is_https:
raw = request.cookies.get("__MCP_CONSENT_BINDING")
if not raw:
@@ -220,6 +221,7 @@ class ConsentMixin:
httponly=True,
samesite="lax",
path="/",
+ domain=self._consent_cookie_domain,
)
return
payload_bytes = json.dumps(bindings, separators=(",", ":")).encode()
@@ -233,6 +235,7 @@ class ConsentMixin:
httponly=True,
samesite="lax",
path="/",
+ domain=self._consent_cookie_domain,
)
def _set_consent_binding_cookie(
diff --git a/fastmcp_slim/fastmcp/server/auth/oauth_proxy/proxy.py b/fastmcp_slim/fastmcp/server/auth/oauth_proxy/proxy.py
index 760552bcc..985f057fb 100644
--- a/fastmcp_slim/fastmcp/server/auth/oauth_proxy/proxy.py
+++ b/fastmcp_slim/fastmcp/server/auth/oauth_proxy/proxy.py
@@ -332,6 +332,7 @@ class OAuthProxy(OAuthProvider, ConsentMixin):
jwt_signing_key: str | bytes | None = None,
# Consent screen configuration
require_authorization_consent: bool | Literal["remember", "external"] = True,
+ consent_cookie_domain: str | None = None,
consent_csp_policy: str | None = None,
# Token expiry fallback
fallback_access_token_expiry_seconds: int | None = None,
@@ -403,6 +404,14 @@ class OAuthProxy(OAuthProvider, ConsentMixin):
FastMCP does not provide or verify those external protections.
- False: skip consent entirely. SECURITY WARNING: only set to
False for local development or testing environments.
+ consent_cookie_domain: Explicit domain for consent cookies. By default,
+ FastMCP uses host-only ``__Host-`` cookies on HTTPS. Set this only
+ when a hosting layer adds a ``Domain`` attribute to response cookies.
+ The value must exactly match the hostname in ``base_url``; parent
+ domains are rejected. Configuring a domain uses ``__Secure-`` cookies
+ and allows them to reach child subdomains, weakening browser-enforced
+ host isolation. Cookie signing, ``Secure``, ``HttpOnly``, and
+ ``SameSite=Lax`` remain enabled.
consent_csp_policy: Content Security Policy for the consent page.
If None (default), uses the built-in CSP policy with appropriate directives.
If empty string "", disables CSP entirely (no meta tag is rendered).
@@ -517,7 +526,27 @@ class OAuthProxy(OAuthProvider, ConsentMixin):
self._require_authorization_consent: bool | Literal["remember", "external"] = (
require_authorization_consent
)
+ self._consent_cookie_domain: str | None = None
+ if consent_cookie_domain is not None:
+ assert self.base_url is not None
+ assert self.base_url.host is not None
+ configured_domain = consent_cookie_domain.lower().rstrip(".")
+ base_host = self.base_url.host.lower().rstrip(".")
+ if configured_domain != base_host:
+ raise ValueError(
+ "consent_cookie_domain must exactly match the hostname in base_url"
+ )
+ if self.base_url.scheme != "https":
+ raise ValueError("consent_cookie_domain requires an HTTPS base_url")
+ self._consent_cookie_domain = configured_domain
self._consent_csp_policy: str | None = consent_csp_policy
+ if self._consent_cookie_domain is not None:
+ logger.warning(
+ "Consent cookies are scoped to %s and use __Secure- instead of "
+ "__Host-. Child subdomains can receive or replace these cookies; "
+ "only use this setting when those hosts are trusted.",
+ self._consent_cookie_domain,
+ )
if require_authorization_consent == "external":
logger.info(
"Built-in consent screen disabled; consent is handled externally."
diff --git a/fastmcp_slim/fastmcp/server/auth/oidc_proxy.py b/fastmcp_slim/fastmcp/server/auth/oidc_proxy.py
index 5e4086c7a..69413a8fd 100644
--- a/fastmcp_slim/fastmcp/server/auth/oidc_proxy.py
+++ b/fastmcp_slim/fastmcp/server/auth/oidc_proxy.py
@@ -234,6 +234,7 @@ class OIDCProxy(OAuthProxy):
token_endpoint_auth_method: str | None = None,
# Consent screen configuration
require_authorization_consent: bool | Literal["remember", "external"] = True,
+ consent_cookie_domain: str | None = None,
consent_csp_policy: str | None = None,
forward_resource: bool = True,
# Extra parameters
@@ -310,6 +311,11 @@ class OIDCProxy(OAuthProxy):
but the warning is suppressed as an operator acknowledgment that
equivalent protections are enforced externally.
SECURITY WARNING: Only set to False for local development or testing environments.
+ consent_cookie_domain: Explicit domain for consent cookies. By default,
+ FastMCP uses host-only ``__Host-`` cookies on HTTPS. Set this only
+ for hosting layers that add a ``Domain`` attribute. The value must
+ exactly match the hostname in ``base_url`` and causes ``__Secure-``
+ cookies to be used, allowing child subdomains to receive them.
consent_csp_policy: Content Security Policy for the consent page.
If None (default), uses the built-in CSP policy with appropriate directives.
If empty string "", disables CSP entirely (no meta tag is rendered).
@@ -430,6 +436,7 @@ class OIDCProxy(OAuthProxy):
"jwt_signing_key": jwt_signing_key,
"token_endpoint_auth_method": token_endpoint_auth_method,
"require_authorization_consent": require_authorization_consent,
+ "consent_cookie_domain": consent_cookie_domain,
"consent_csp_policy": consent_csp_policy,
"forward_resource": forward_resource,
"fallback_access_token_expiry_seconds": fallback_access_token_expiry_seconds,
diff --git a/fastmcp_slim/fastmcp/server/auth/providers/azure.py b/fastmcp_slim/fastmcp/server/auth/providers/azure.py
index b0cf9d360..b38acf9ec 100644
--- a/fastmcp_slim/fastmcp/server/auth/providers/azure.py
+++ b/fastmcp_slim/fastmcp/server/auth/providers/azure.py
@@ -113,6 +113,7 @@ class AzureProvider(OAuthProxy):
client_storage: AsyncKeyValue | None = None,
jwt_signing_key: str | bytes | None = None,
require_authorization_consent: bool | Literal["remember", "external"] = True,
+ consent_cookie_domain: str | None = None,
consent_csp_policy: str | None = None,
forward_resource: bool = True,
fallback_refresh_token_expiry_seconds: int | None = None,
@@ -177,6 +178,12 @@ class AzureProvider(OAuthProxy):
but the warning is suppressed as an operator acknowledgment that
equivalent protections are enforced externally.
SECURITY WARNING: Only set to False for local development or testing environments.
+ consent_cookie_domain: Explicit domain for consent cookies. By default,
+ FastMCP uses host-only ``__Host-`` cookies on HTTPS. Set this only
+ for hosting layers such as Azure Functions that add a ``Domain``
+ attribute. The value must exactly match the hostname in ``base_url``
+ and causes ``__Secure-`` cookies to be used, allowing child
+ subdomains to receive them.
http_client: Optional httpx2.AsyncClient for connection pooling in JWKS fetches.
When provided, the client is reused for JWT key fetches and the caller
is responsible for its lifecycle. When None (default), a fresh client is created per fetch.
@@ -273,6 +280,7 @@ class AzureProvider(OAuthProxy):
client_storage=client_storage,
jwt_signing_key=jwt_signing_key,
require_authorization_consent=require_authorization_consent,
+ consent_cookie_domain=consent_cookie_domain,
consent_csp_policy=consent_csp_policy,
forward_resource=forward_resource,
fallback_refresh_token_expiry_seconds=fallback_refresh_token_expiry_seconds,
diff --git a/tests/server/auth/providers/test_azure.py b/tests/server/auth/providers/test_azure.py
index 704af3ab4..981b4f3e0 100644
--- a/tests/server/auth/providers/test_azure.py
+++ b/tests/server/auth/providers/test_azure.py
@@ -66,6 +66,23 @@ class TestAzureProvider:
assert provider._redirect_path == "/auth/callback"
# Azure provider defaults are set but we can't easily verify them without accessing internals
+ def test_explicit_consent_cookie_domain(self, memory_storage: MemoryStore):
+ provider = AzureProvider(
+ client_id="test_client",
+ client_secret="test_secret",
+ tenant_id="test-tenant",
+ base_url="https://myserver.com",
+ required_scopes=["read"],
+ jwt_signing_key="test-secret",
+ client_storage=memory_storage,
+ consent_cookie_domain="myserver.com",
+ )
+
+ assert (
+ provider._cookie_name("MCP_CONSENT_STATE") == "__Secure-MCP_CONSENT_STATE"
+ )
+ assert provider._consent_cookie_domain == "myserver.com"
+
def test_offline_access_automatically_included(self, memory_storage: MemoryStore):
"""Test that offline_access is automatically added to get refresh tokens."""
# Without specifying offline_access
diff --git a/tests/server/auth/test_oauth_consent_page.py b/tests/server/auth/test_oauth_consent_page.py
index 1cab95190..2f092eff8 100644
--- a/tests/server/auth/test_oauth_consent_page.py
+++ b/tests/server/auth/test_oauth_consent_page.py
@@ -64,6 +64,22 @@ def oauth_proxy_https_remember():
)
+@pytest.fixture
+def oauth_proxy_https_with_cookie_domain():
+ """OAuthProxy using an explicit cookie domain for platform compatibility."""
+ return OAuthProxy(
+ upstream_authorization_endpoint="https://github.com/login/oauth/authorize",
+ upstream_token_endpoint="https://github.com/login/oauth/access_token",
+ upstream_client_id="client-id",
+ upstream_client_secret="client-secret",
+ token_verifier=_Verifier(),
+ base_url="https://myserver.example",
+ client_storage=MemoryStore(),
+ jwt_signing_key="test-secret",
+ consent_cookie_domain="myserver.example",
+ )
+
+
async def _start_flow(
proxy: OAuthProxy, client_id: str, redirect: str
) -> tuple[str, str]:
@@ -100,6 +116,143 @@ def _extract_csrf(html: str) -> str | None:
return m.group(1) if m else None
+class TestConsentCookieDomain:
+ def test_parent_domain_is_rejected(self):
+ with pytest.raises(
+ ValueError,
+ match="consent_cookie_domain must exactly match the hostname in base_url",
+ ):
+ OAuthProxy(
+ upstream_authorization_endpoint="https://github.com/login/oauth/authorize",
+ upstream_token_endpoint="https://github.com/login/oauth/access_token",
+ upstream_client_id="client-id",
+ upstream_client_secret="client-secret",
+ token_verifier=_Verifier(),
+ base_url="https://myserver.example",
+ client_storage=MemoryStore(),
+ jwt_signing_key="test-secret",
+ consent_cookie_domain="example",
+ )
+
+ def test_domain_requires_https(self):
+ with pytest.raises(
+ ValueError, match="consent_cookie_domain requires an HTTPS base_url"
+ ):
+ OAuthProxy(
+ upstream_authorization_endpoint="https://github.com/login/oauth/authorize",
+ upstream_token_endpoint="https://github.com/login/oauth/access_token",
+ upstream_client_id="client-id",
+ upstream_client_secret="client-secret",
+ token_verifier=_Verifier(),
+ base_url="http://myserver.example",
+ client_storage=MemoryStore(),
+ jwt_signing_key="test-secret",
+ consent_cookie_domain="myserver.example",
+ )
+
+ async def test_explicit_domain_completes_consent_with_secure_cookies(
+ self, oauth_proxy_https_with_cookie_domain
+ ):
+ txn_id, _ = await _start_flow(
+ oauth_proxy_https_with_cookie_domain,
+ "explicit-domain-client",
+ "http://localhost:6000/callback",
+ )
+ app = Starlette(routes=oauth_proxy_https_with_cookie_domain.get_routes())
+
+ with TestClient(app, base_url="https://myserver.example") as client:
+ consent = client.get(f"/consent?txn_id={txn_id}")
+ csrf = _extract_csrf(consent.text)
+ assert csrf
+ set_cookie = consent.headers.get("set-cookie", "")
+ assert "__Secure-MCP_CONSENT_STATE=" in set_cookie
+ assert "__Host-" not in set_cookie
+ assert "Secure" in set_cookie
+ assert "HttpOnly" in set_cookie
+ assert "SameSite=lax" in set_cookie
+ assert "Domain=myserver.example" in set_cookie
+
+ response = client.post(
+ "/consent",
+ data={
+ "action": "approve",
+ "txn_id": txn_id,
+ "csrf_token": csrf,
+ },
+ follow_redirects=False,
+ )
+
+ assert response.status_code in (302, 303)
+ binding_cookie = response.headers.get("set-cookie", "")
+ assert "__Secure-MCP_CONSENT_BINDING=" in binding_cookie
+ assert "Domain=myserver.example" in binding_cookie
+
+ async def test_explicit_domain_does_not_accept_host_prefix(
+ self, oauth_proxy_https_with_cookie_domain
+ ):
+ txn_id, _ = await _start_flow(
+ oauth_proxy_https_with_cookie_domain,
+ "wrong-prefix-client",
+ "http://localhost:6001/callback",
+ )
+ app = Starlette(routes=oauth_proxy_https_with_cookie_domain.get_routes())
+
+ with TestClient(app, base_url="https://myserver.example") as browser:
+ consent = browser.get(f"/consent?txn_id={txn_id}")
+ csrf = _extract_csrf(consent.text)
+ assert csrf
+ signed_state = consent.cookies["__Secure-MCP_CONSENT_STATE"]
+
+ with TestClient(app, base_url="https://myserver.example") as browser:
+ browser.cookies.set("__Host-MCP_CONSENT_STATE", signed_state)
+ response = browser.post(
+ "/consent",
+ data={
+ "action": "approve",
+ "txn_id": txn_id,
+ "csrf_token": csrf,
+ },
+ follow_redirects=False,
+ )
+
+ assert response.status_code == 403
+
+ async def test_default_does_not_accept_secure_prefix(self, oauth_proxy_https):
+ txn_id, _ = await _start_flow(
+ oauth_proxy_https,
+ "default-policy-client",
+ "http://localhost:6002/callback",
+ )
+ app = Starlette(routes=oauth_proxy_https.get_routes())
+
+ with TestClient(app) as browser:
+ consent = browser.get(f"/consent?txn_id={txn_id}")
+ csrf = _extract_csrf(consent.text)
+ assert csrf
+ signed_state = consent.cookies["__Host-MCP_CONSENT_STATE"]
+
+ with TestClient(app) as browser:
+ browser.cookies.set("__Secure-MCP_CONSENT_STATE", signed_state)
+ response = browser.post(
+ "/consent",
+ data={
+ "action": "approve",
+ "txn_id": txn_id,
+ "csrf_token": csrf,
+ },
+ follow_redirects=False,
+ )
+
+ assert response.status_code == 403
+
+ def test_default_remains_host_only(self, oauth_proxy_https):
+ assert (
+ oauth_proxy_https._cookie_name("MCP_CONSENT_STATE")
+ == "__Host-MCP_CONSENT_STATE"
+ )
+ assert oauth_proxy_https._consent_cookie_domain is None
+
+
class TestConsentPageServerIcon:
"""Tests for server icon display in OAuth consent screen."""
diff --git a/tests/server/auth/test_oidc_proxy.py b/tests/server/auth/test_oidc_proxy.py
index 755049120..2bad5140c 100644
--- a/tests/server/auth/test_oidc_proxy.py
+++ b/tests/server/auth/test_oidc_proxy.py
@@ -489,6 +489,30 @@ class TestOIDCProxyInitialization:
call_args = mock_get.call_args
assert call_args[1]["timeout_seconds"] == 12
+ def test_explicit_consent_cookie_domain(self, valid_oidc_configuration_dict):
+ with patch(
+ "fastmcp.server.auth.oidc_proxy.OIDCConfiguration.get_oidc_configuration"
+ ) as mock_get:
+ oidc_config = OIDCConfiguration.model_validate(
+ valid_oidc_configuration_dict
+ )
+ mock_get.return_value = oidc_config
+
+ proxy = OIDCProxy(
+ config_url=TEST_CONFIG_URL,
+ client_id=TEST_CLIENT_ID,
+ client_secret=TEST_CLIENT_SECRET,
+ base_url=TEST_BASE_URL,
+ jwt_signing_key="test-secret",
+ consent_cookie_domain="example.com",
+ )
+
+ validate_proxy(mock_get, proxy, oidc_config)
+ assert (
+ proxy._cookie_name("MCP_CONSENT_STATE") == "__Secure-MCP_CONSENT_STATE"
+ )
+ assert proxy._consent_cookie_domain == "example.com"
+
def test_token_verifier_initialization(self, valid_oidc_configuration_dict):
"""Test token verifier initialization."""
with patch(