A new screen package with the fix for the CVE-2021-26937 within CentOS 6 extended lifecycle support has been rolled out to 100% and is now available for download from our production repository.
Errata: https://errata.cloudlinux.com/els6/CLSA-2021-1618497131.html
screen-4.0.3-20.el6.cloudlinux.els6
yum update screen*