1 files changed, 10 insertions, 2 deletions
diff --git a/lib/webrick/accesslog.rb b/lib/webrick/accesslog.rb
index f97769545e..75a3a3e694 100644
--- a/lib/webrick/accesslog.rb
+++ b/lib/webrick/accesslog.rb
@@ -53,15 +53,23 @@ module WEBrick
          when ?e, ?i, ?n, ?o
            raise AccessLogError,
              "parameter is required for \"#{spec}\"" unless param
-           params[spec][param] || "-"
+           param = params[spec][param] ? escape(param) : "-"
          when ?t
            params[spec].strftime(param || CLF_TIME_FORMAT)
          when ?%
            "%"
          else
-           params[spec]
+           escape(params[spec].to_s)
          end
       }
     end
+
+    def escape(data)
+      if data.tainted?
+        data.gsub(/[[:cntrl:]\\]+/) {$&.dump[1...-1]}.untaint
+      else
+        data
+      end
+    end
   end
 end