diff --git a/CHANGELOG.md b/CHANGELOG.md
index 85cb1fc2a..b8f796794 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,16 +10,16 @@ All notable changes to this project will be documented in this file. For info on
 
 - [CVE-2023-27530] Introduce multipart_total_part_limit to limit total parts
 
-## [2.2.6.2] - 2022-01-17
+## [2.2.6.2] - 2023-01-17
 
 - [CVE-2022-44570] Fix ReDoS in Rack::Utils.get_byte_ranges
 
-## [2.2.6.1] - 2022-01-17
+## [2.2.6.1] - 2023-01-17
 
 - [CVE-2022-44571] Fix ReDoS vulnerability in multipart parser
 - [CVE-2022-44572] Forbid control characters in attributes (also ReDoS)
 
-## [2.2.6] - 2022-01-17
+## [2.2.6] - 2023-01-17
 
 - Extend `Rack::MethodOverride` to handle `QueryParser::ParamsTooDeepError` error. ([#2011](https://github.com/rack/rack/pull/2011), [@byroot](https://github.com/byroot))
 
diff --git a/lib/rack/request.rb b/lib/rack/request.rb
index fea984590..0bd8ee458 100644
--- a/lib/rack/request.rb
+++ b/lib/rack/request.rb
@@ -608,7 +608,7 @@ def split_header(value)
           (?<ip4>[\d\.]+)
           |
           # A hostname:
-          (?<name>[a-zA-Z0-9\.\-]+)
+          (?<name>[a-zA-Z0-9\.\-_]+)
         )
         # The optional port:
         (:(?<port>\d+))?
diff --git a/lib/rack/version.rb b/lib/rack/version.rb
index d451de434..1aee4daa7 100644
--- a/lib/rack/version.rb
+++ b/lib/rack/version.rb
@@ -20,7 +20,7 @@ def self.version
     VERSION.join(".")
   end
 
-  RELEASE = "2.2.6.4"
+  RELEASE = "2.2.7"
 
   # Return the Rack release as a dotted string.
   def self.release
diff --git a/test/spec_request.rb b/test/spec_request.rb
index 51cfcdc88..db52dea29 100644
--- a/test/spec_request.rb
+++ b/test/spec_request.rb
@@ -121,6 +121,11 @@ class RackRequestTest < Minitest::Spec
     req.host.must_equal "123foo.example.com"
     req.hostname.must_equal "123foo.example.com"
 
+    req = make_request \
+      Rack::MockRequest.env_for("/", "HTTP_HOST" => "some_service:3001")
+    req.host.must_equal "some_service"
+    req.hostname.must_equal "some_service"
+
     req = make_request \
       Rack::MockRequest.env_for("/", "SERVER_NAME" => "example.org", "SERVER_PORT" => "9292")
     req.host.must_equal "example.org"
@@ -156,6 +161,10 @@ class RackRequestTest < Minitest::Spec
       Rack::MockRequest.env_for("/", "HTTP_HOST" => "www2.example.org:81")
     req.port.must_equal 81
 
+    req = make_request \
+      Rack::MockRequest.env_for("/", "HTTP_HOST" => "some_service:3001")
+    req.port.must_equal 3001
+
     req = make_request \
       Rack::MockRequest.env_for("/", "SERVER_NAME" => "example.org", "SERVER_PORT" => "9292")
     req.port.must_equal 9292