3 files changed, 37 insertions, 4 deletions
diff --git a/actionpack/CHANGELOG.md b/actionpack/CHANGELOG.md
index 453da28309..07063c953a 100644
--- a/actionpack/CHANGELOG.md
+++ b/actionpack/CHANGELOG.md
@@ -1,3 +1,10 @@
+*   Restore handling of a bare `Authorization` header, without `token=`
+    prefix.
+
+    Fixes #17108.
+
+    *Guo Xiang Tan*
+
 *   Deprecate use of string keys in URL helpers.
 
     Use symbols instead.
diff --git a/actionpack/lib/action_controller/metal/http_authentication.rb b/actionpack/lib/action_controller/metal/http_authentication.rb
index 2717a41d36..fd578d60ca 100644
--- a/actionpack/lib/action_controller/metal/http_authentication.rb
+++ b/actionpack/lib/action_controller/metal/http_authentication.rb
@@ -397,6 +397,7 @@ module ActionController
     #
     #   RewriteRule ^(.*)$ dispatch.fcgi [E=X-HTTP_AUTHORIZATION:%{HTTP:Authorization},QSA,L]
     module Token
+      TOKEN_KEY = 'token='
       TOKEN_REGEX = /^Token /
       AUTHN_PAIR_DELIMITERS = /(?:,|;|\t+)/
       extend self
@@ -471,7 +472,13 @@ module ActionController
       # pairs by the standardized <tt>:</tt>, <tt>;</tt>, or <tt>\t</tt>
       # delimiters defined in +AUTHN_PAIR_DELIMITERS+.
       def raw_params(auth)
-        auth.sub(TOKEN_REGEX, '').split(/\s*#{AUTHN_PAIR_DELIMITERS}\s*/)
+        _raw_params = auth.sub(TOKEN_REGEX, '').split(/\s*#{AUTHN_PAIR_DELIMITERS}\s*/)
+
+        if !(_raw_params.first =~ %r{\A#{TOKEN_KEY}})
+          _raw_params[0] = "#{TOKEN_KEY}#{_raw_params.first}"
+        end
+
+        _raw_params
       end
 
       # Encodes the given token and options into an Authorization header value.
@@ -481,7 +488,7 @@ module ActionController
       #
       # Returns String.
       def encode_credentials(token, options = {})
-        values = ["token=#{token.to_s.inspect}"] + options.map do |key, value|
+        values = ["#{TOKEN_KEY}#{token.to_s.inspect}"] + options.map do |key, value|
           "#{key}=#{value.to_s.inspect}"
         end
         "Token #{values * ", "}"
diff --git a/actionpack/test/controller/http_token_authentication_test.rb b/actionpack/test/controller/http_token_authentication_test.rb
index 8c6c8a0aa7..a758df2ec6 100644
--- a/actionpack/test/controller/http_token_authentication_test.rb
+++ b/actionpack/test/controller/http_token_authentication_test.rb
@@ -162,17 +162,36 @@ class HttpTokenAuthenticationTest < ActionController::TestCase
     assert_equal(expected, actual)
   end
 
+  test "token_and_options returns right token when token key is not specified in header" do
+    token = "rcHu+HzSFw89Ypyhn/896A="
+
+    actual = ActionController::HttpAuthentication::Token.token_and_options(
+      sample_request_without_token_key(token)
+    ).first
+
+    expected = token
+    assert_equal(expected, actual)
+  end
+
   private
 
     def sample_request(token, options = {nonce: "def"})
       authorization = options.inject([%{Token token="#{token}"}]) do |arr, (k, v)|
         arr << "#{k}=\"#{v}\""
       end.join(", ")
-      @sample_request ||= OpenStruct.new authorization: authorization
+      mock_authorization_request(authorization)
     end
 
     def malformed_request
-      @malformed_request ||= OpenStruct.new authorization: %{Token token=}
+      mock_authorization_request(%{Token token=})
+    end
+
+    def sample_request_without_token_key(token)
+      mock_authorization_request(%{Token #{token}})
+    end
+
+    def mock_authorization_request(authorization)
+      OpenStruct.new(authorization: authorization)
     end
 
     def encode_credentials(token, options = {})