Merge pull request #320 from DevamShah/fix-cors-credentials-and-icon-traversal

fix: wildcard CORS + credentials spec violation, path-traversal guard on /icons proxy

tests/unit/test_cors_middleware.py

@@ -0,0 +1,94 @@
+"""Unit tests for CORS middleware configuration.
+
+Verifies that the wildcard-origins + allow_credentials=True spec violation
+(CORS spec §3.2, Fetch §4.7) has been removed.  Browsers silently strip
+credentials when the response carries Access-Control-Allow-Origin: * paired
+with Access-Control-Allow-Credentials: true, so the old config was both
+broken and misleading.
+"""
+
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+from fastapi.testclient import TestClient
+
+from agentic_security.middleware.cors import setup_cors
+
+
+def _get_cors_options(app: FastAPI) -> dict:
+    """Extract CORS middleware options from the app's middleware stack."""
+    for middleware in app.user_middleware:
+        if middleware.cls is CORSMiddleware:
+            return middleware.kwargs
+    return {}
+
+
+class TestCorsSetup:
+    """CORS middleware is configured correctly."""
+
+    def test_cors_middleware_is_registered(self):
+        """setup_cors adds CORSMiddleware to the app."""
+        app = FastAPI()
+        setup_cors(app)
+        cls_names = [m.cls.__name__ for m in app.user_middleware]
+        assert "CORSMiddleware" in cls_names
+
+    def test_wildcard_origins_without_credentials(self):
+        """allow_origins=['*'] must not be paired with allow_credentials=True.
+
+        The combination is forbidden by the CORS spec and causes browsers to
+        silently drop credentials on every cross-origin request.
+        """
+        app = FastAPI()
+        setup_cors(app)
+        opts = _get_cors_options(app)
+        allow_origins = opts.get("allow_origins", [])
+        allow_credentials = opts.get("allow_credentials", False)
+
+        if "*" in allow_origins or allow_origins == ["*"]:
+            assert not allow_credentials, (
+                "allow_origins=['*'] with allow_credentials=True is invalid per "
+                "the CORS spec — browsers reject it and credentials are silently dropped"
+            )
+
+    def test_cors_allows_cross_origin_requests(self):
+        """Cross-origin preflight requests return a 200 with CORS headers."""
+        app = FastAPI()
+
+        @app.get("/probe")
+        async def probe():
+            return {"ok": True}
+
+        setup_cors(app)
+        client = TestClient(app, raise_server_exceptions=True)
+
+        response = client.options(
+            "/probe",
+            headers={
+                "Origin": "http://localhost:3000",
+                "Access-Control-Request-Method": "GET",
+            },
+        )
+        assert response.status_code == 200
+        assert "access-control-allow-origin" in response.headers
+
+    def test_cors_no_credentials_header_with_wildcard(self):
+        """With wildcard origins, the response must not include
+        Access-Control-Allow-Credentials: true."""
+        app = FastAPI()
+
+        @app.get("/probe")
+        async def probe():
+            return {"ok": True}
+
+        setup_cors(app)
+        client = TestClient(app)
+        response = client.get("/probe", headers={"Origin": "http://evil.example.com"})
+
+        acao = response.headers.get("access-control-allow-origin", "")
+        acac = response.headers.get("access-control-allow-credentials", "false")
+
+        if acao == "*":
+            assert acac.lower() != "true", (
+                "Wildcard ACAO + ACAC:true is a spec violation (RFC 6454 §7.2, "
+                "Fetch §4.7) and silently breaks credentialed cross-origin requests"
+            )