diff --git a/kubernetes/linux/setup.sh b/kubernetes/linux/setup.sh
index b8829e13b..17cfb3f77 100644
--- a/kubernetes/linux/setup.sh
+++ b/kubernetes/linux/setup.sh
@@ -49,8 +49,6 @@ sudo apt-get install software-properties-common -y
 sudo apt-add-repository ppa:brightbox/ruby-ng -y
 sudo apt-get update
 sudo apt-get install ruby2.6 ruby2.6-dev gcc make -y
-# to fix CVE-2020-10663
-gem update json -v 2.5.1
 # fluentd v1 gem
 gem install fluentd -v "1.12.2" --no-document
 fluentd --setup ./fluent