From cb83133c4ef6d2362f938c2ab00cfa5228599a6f Mon Sep 17 00:00:00 2001
From: Yurii Motov <yurii.motov.monte@gmail.com>
Date: Tue, 20 Jan 2026 12:03:39 +0100
Subject: [PATCH] Revert "Fix HTTP Basic realm handling (RFC 7617)"

This reverts commit e8c08fc843dc12c8f100065fc442dea749eeff11.
---
 fastapi/security/http.py         | 13 +++++++++++--
 tests/test_security_http_base.py | 18 +-----------------
 2 files changed, 12 insertions(+), 19 deletions(-)

diff --git a/fastapi/security/http.py b/fastapi/security/http.py
index 25cb4e376..b4c3bc6d8 100644
--- a/fastapi/security/http.py
+++ b/fastapi/security/http.py
@@ -152,7 +152,14 @@ class HTTPBasic(HTTPBase):
                 """
             ),
         ] = None,
-        realm: Annotated[str, Doc("HTTP Basic authentication realm.")] = "fastapi",
+        realm: Annotated[
+            Optional[str],
+            Doc(
+                """
+                HTTP Basic authentication realm.
+                """
+            ),
+        ] = None,
         description: Annotated[
             Optional[str],
             Doc(
@@ -190,7 +197,9 @@ class HTTPBasic(HTTPBase):
         self.auto_error = auto_error
 
     def make_authenticate_headers(self) -> dict[str, str]:
-        return {"WWW-Authenticate": f'Basic realm="{self.realm}"'}
+        if self.realm:
+            return {"WWW-Authenticate": f'Basic realm="{self.realm}"'}
+        return {"WWW-Authenticate": "Basic"}
 
     async def __call__(  # type: ignore
         self, request: Request
diff --git a/tests/test_security_http_base.py b/tests/test_security_http_base.py
index 1e948f218..8cf259a75 100644
--- a/tests/test_security_http_base.py
+++ b/tests/test_security_http_base.py
@@ -1,5 +1,4 @@
-from fastapi import Depends, FastAPI, Security
-from fastapi.security import HTTPBasic
+from fastapi import FastAPI, Security
 from fastapi.security.http import HTTPAuthorizationCredentials, HTTPBase
 from fastapi.testclient import TestClient
 
@@ -54,18 +53,3 @@ def test_openapi_schema():
             "securitySchemes": {"HTTPBase": {"type": "http", "scheme": "Other"}}
         },
     }
-
-
-def test_http_basic_includes_realm():
-    app = FastAPI()
-    security = HTTPBasic(realm="MyRealm")
-
-    @app.get("/")
-    def read_root(credentials=Depends(security)):
-        return {"ok": True}
-
-    client = TestClient(app)
-    response = client.get("/")
-
-    assert response.status_code == 401
-    assert response.headers["WWW-Authenticate"] == 'Basic realm="MyRealm"'