diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4d939af..52ca43c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -75,6 +75,13 @@ Note that 0.3.3 was never released; 0.3.4 follows 0.3.2.
   are no longer read; `clear()` removes them.
   ([#110](https://github.com/allen0099/FastAPI-CacheX/issues/110))
 
+- **The session middleware reads `Authorization: bearer <token>` in any
+  letter case.** Authentication scheme names are case-insensitive (RFC 9110
+  §11.1), but only the exact `Bearer ` prefix was recognised, so a client
+  sending `bearer` got no session. More than one space before the token is
+  accepted too, and a header without a token no longer yields an empty one.
+  ([#166](https://github.com/allen0099/FastAPI-CacheX/issues/166))
+
 ## [0.3.7] - 2026-09-25
 
 ### Added
diff --git a/fastapi_cachex/session/middleware.py b/fastapi_cachex/session/middleware.py
index 9594b8b..bcbd4d5 100644
--- a/fastapi_cachex/session/middleware.py
+++ b/fastapi_cachex/session/middleware.py
@@ -111,10 +111,13 @@ def _extract_header_token(
 
         elif source == "bearer":
             if config.use_bearer_token:
-                auth_header = connection.headers.get("authorization")
-                if auth_header and auth_header.startswith("Bearer "):
-                    bearer_prefix_len = 7
-                    token_value = auth_header[bearer_prefix_len:]
+                # The scheme name is case-insensitive (RFC 9110 §11.1) and is
+                # followed by one or more spaces (RFC 6750 §2.1).
+                scheme, _, token_value = connection.headers.get(
+                    "authorization", ""
+                ).partition(" ")
+                token_value = token_value.lstrip(" ")
+                if scheme.lower() == "bearer" and token_value:
                     logger.debug("Token extracted from bearer auth")
                     return token_value
 
diff --git a/tests/session/test_middleware.py b/tests/session/test_middleware.py
index 43ef618..30efcbd 100644
--- a/tests/session/test_middleware.py
+++ b/tests/session/test_middleware.py
@@ -588,6 +588,38 @@ def test_bearer_is_used_when_the_header_source_finds_nothing(
     assert token == "from-bearer"
 
 
+@pytest.mark.parametrize(
+    "authorization",
+    [
+        "Bearer from-bearer",
+        "bearer from-bearer",
+        "BEARER from-bearer",
+        "Bearer   from-bearer",
+    ],
+)
+def test_bearer_scheme_is_matched_case_insensitively(
+    config: SessionConfig, authorization: str
+) -> None:
+    """Auth schemes are case-insensitive (RFC 9110 §11.1), and RFC 6750 allows
+    more than one space before the token (#166).
+    """
+    token = _extract_header_token(_connection({"Authorization": authorization}), config)
+
+    assert token == "from-bearer"
+
+
+@pytest.mark.parametrize(
+    "authorization",
+    ["Bearer", "Bearer ", "Bearer   ", "Basic from-bearer", "Bearerfrom-bearer"],
+)
+def test_an_empty_or_non_bearer_authorization_header_yields_no_token(
+    config: SessionConfig, authorization: str
+) -> None:
+    token = _extract_header_token(_connection({"Authorization": authorization}), config)
+
+    assert token is None
+
+
 def test_header_wins_over_bearer_when_both_are_present(
     config: SessionConfig,
 ) -> None: