diff --git a/lib/webrick/httpservlet/cgihandler.rb b/lib/webrick/httpservlet/cgihandler.rb
index 450aa38..873ddd5 100644
--- a/lib/webrick/httpservlet/cgihandler.rb
+++ b/lib/webrick/httpservlet/cgihandler.rb
@@ -96,7 +96,9 @@ def do_GET(req, res)
           "Premature end of script headers: #{@script_filename}" if body.nil?
 
         begin
-          header = HTTPUtils::parse_header(raw_header)
+          header = HTTPUtils::parse_header(raw_header,
+            header_line_regexp: REGEXP_CGI_HEADER_LINE ,
+            continued_header_line_regexp: REGEXP_CONTINUED_CGI_HEADER_LINE)
           if /^(\d+)/ =~ header['status'][0]
             res.status = $1.to_i
             header.delete('status')
@@ -119,6 +121,10 @@ def do_GET(req, res)
       end
       alias do_POST do_GET
 
+      REGEXP_CGI_HEADER_LINE = /^([A-Za-z0-9!\#$%&'*+\-.^_`|~]+):([^\r\n\0]*?)\r?\n\z/m
+      REGEXP_CONTINUED_CGI_HEADER_LINE = /^[ \t]+([^\r\n\0]*?)\r?\n/m
+      private_constant :REGEXP_CGI_HEADER_LINE, :REGEXP_CONTINUED_CGI_HEADER_LINE
+
       # :startdoc:
     end
 
diff --git a/lib/webrick/httputils.rb b/lib/webrick/httputils.rb
index e2c2a40..53c9ba2 100644
--- a/lib/webrick/httputils.rb
+++ b/lib/webrick/httputils.rb
@@ -148,10 +148,6 @@ def mime_type(filename, mime_tab)
     end
     module_function :mime_type
 
-    ##
-    # Parses an HTTP header +raw+ into a hash of header fields with an Array
-    # of values.
-
     class SplitHeader < Array
       def join(separator = ", ")
         super
@@ -168,17 +164,28 @@ def join(separator = "; ")
       "cookie" => CookieHeader,
     })
 
-    def parse_header(raw)
+    REGEXP_HEADER_LINE = /^([A-Za-z0-9!\#$%&'*+\-.^_`|~]+):([^\r\n\0]*?)\r\n\z/m
+    REGEXP_CONTINUED_HEADER_LINE = /^[ \t]+([^\r\n\0]*?)\r\n/m
+
+    ##
+    # Parses an HTTP header +raw+ into a hash of header fields with an Array
+    # of values. The header is expected to end with \r\n. If the header is in CGI
+    # format, use +header_line_regexp+ and +continued_header_line_regexp+ to
+    # parse the header lines. The default values are REGEXP_HEADER_LINE and
+    # REGEXP_CONTINUED_HEADER_LINE.
+
+    def parse_header(raw, header_line_regexp: REGEXP_HEADER_LINE, continued_header_line_regexp: REGEXP_CONTINUED_HEADER_LINE)
       header = Hash.new([].freeze)
       field = nil
+
       raw.each_line{|line|
         case line
-        when /^([A-Za-z0-9!\#$%&'*+\-.^_`|~]+):([^\r\n\0]*?)\r\n\z/om
+        when header_line_regexp
           field, value = $1, $2
           field.downcase!
           header[field] = HEADER_CLASSES[field].new unless header.has_key?(field)
           header[field] << value
-        when /^[ \t]+([^\r\n\0]*?)\r\n/om
+        when continued_header_line_regexp
           unless field
             raise HTTPStatus::BadRequest, "bad header '#{line}'."
           end
diff --git a/sig/httputils.rbs b/sig/httputils.rbs
index a554cdf..1c69cd4 100644
--- a/sig/httputils.rbs
+++ b/sig/httputils.rbs
@@ -26,7 +26,7 @@ module WEBrick
 
     HEADER_CLASSES: Hash[String, untyped]
 
-    def self?.parse_header: (String raw) -> Hash[String, Array[String]]
+    def self?.parse_header: (String raw, ?header_line_regexp: Regexp, ?continued_header_line_regexp: Regexp) -> Hash[String, Array[String]]
 
     def self?.split_header_value: (String str) -> Array[String]
 
diff --git a/test/webrick/test_cgi.rb b/test/webrick/test_cgi.rb
index a9be8f3..f8e1312 100644
--- a/test/webrick/test_cgi.rb
+++ b/test/webrick/test_cgi.rb
@@ -145,4 +145,15 @@ def test_bad_header
       assert_not_match(CtrlPat, s)
     }
   end
+
+  def test_bare_lf_in_cgi_header
+    TestWEBrick.start_cgi_server do |server, addr, port, log|
+      http = Net::HTTP.new(addr, port)
+      req = Net::HTTP::Get.new("/webrick_bare_lf.cgi")
+      assert_nothing_raised do
+        res = http.request(req)
+        assert_equal res['Content-Type'], 'text/plain'
+      end
+    end
+  end
 end
diff --git a/test/webrick/webrick_bare_lf.cgi b/test/webrick/webrick_bare_lf.cgi
new file mode 100644
index 0000000..add92fe
--- /dev/null
+++ b/test/webrick/webrick_bare_lf.cgi
@@ -0,0 +1,8 @@
+#!ruby
+
+body = "test for bare LF in cgi header"
+
+print "Content-Type: text/plain\n"
+print "Content-Length: #{body.size}\n"
+print "\n"
+print body