commit d23d2f3f6fbb5d787b0dd80675c489a692be23e2
Author: Yusuke Endoh <mame@ruby-lang.org>
Date:   2020-09-29 13:15:58 +0900

    [ruby/webrick] Make it more strict to interpret some headers
    
    Some regexps were too tolerant.
    
    https://github.com/ruby/webrick/commit/8946bb38b4

diff --git lib/webrick/httprequest.rb lib/webrick/httprequest.rb
index c781797092..d1f0889673 100644
--- lib/webrick/httprequest.rb
+++ lib/webrick/httprequest.rb
@@ -227,9 +227,9 @@ def parse(socket=nil)
         raise HTTPStatus::BadRequest, "bad URI `#{@unparsed_uri}'."
       end
 
-      if /close/io =~ self["connection"]
+      if /\Aclose\z/io =~ self["connection"]
         @keep_alive = false
-      elsif /keep-alive/io =~ self["connection"]
+      elsif /\Akeep-alive\z/io =~ self["connection"]
         @keep_alive = true
       elsif @http_version < "1.1"
         @keep_alive = false
@@ -508,7 +508,7 @@ def read_body(socket, block)
       return unless socket
       if tc = self['transfer-encoding']
         case tc
-        when /chunked/io then read_chunked(socket, block)
+        when /\Achunked\z/io then read_chunked(socket, block)
         else raise HTTPStatus::NotImplemented, "Transfer-Encoding: #{tc}."
         end
       elsif self['content-length'] || @remaining_size