You can downgrade Apache back down to Apache 2.4.51 - but you'll also need to be sure that you do not have automatic updates enabled, otherwise your server's just going to upgrade to Apache 2.4.52 on the next automatic package update run.
First you need to determine what RPM version of Apache you have installed:
rpm -qa ea-apache24
It would appear that cPanel released two versions of Apache 2.4.52:
ea-apache24-2.4.52-1.1.1.cpanel.x86_64
ea-apache24-2.4.52-1.1.3.cpanel.x86_64
If you are using Apache 2.4.52, then rpm -qa ea-apache24 will report one of these two versions. I would suspect that most everyone using Apache 2.4.52 on cPanel is using ea-apache24-2.4.52-1.1.3.cpanel.x86_64. I think ea-apache24-2.4.52-1.1.1.cpanel.x86_64 was released and then almost immediately overwritten by ea-apache24-2.4.52-1.1.3.cpanel.x86_64. So the vast majority of folks went from ea-apache24-2.4.51-2.4.1.cpanel.x86_64 straight to ea-apache24-2.4.52-1.1.3.cpanel.x86_64. But it's technically possible someone got ea-apache24-2.4.52-1.1.1.cpanel.x86_64 and never updated to ea-apache24-2.4.52-1.1.3.cpanel.x86_64.
The version you want to get down to is:
ea-apache24-2.4.51-2.4.1.cpanel.x86_64
Which would appear to be the latest version of Apache 2.4.51 that cPanel released
I'm going to assume that you are running ea-apache24-2.4.52-1.1.3.cpanel.x86_64 - and there may be a more eloquent way of doing this - I'm actually going to downgrade twice. The first downgrade will get me to ea-apache24-2.4.52-1.1.1.cpanel.x86_64 and the second downgrade will get me to ea-apache24-2.4.51-2.4.1.cpanel.x86_64 which is what I want. Probably is a more eloquent way of doing this, but by the time I could find it I could have already run the downgrade twice.
If by chance you are using ea-apache24-2.4.52-1.1.1.cpanel.x86_64 then you will only need to downgrade once.
To insure better results, simply do a rpm -qa ea-apache24 after each downgrade until you see ea-apache24-2.4.51-2.4.1.cpanel.x86_64.
Make a note of what version of Apache you have installed from rpm -qa ea-apache24. Remember there is a ea-apache24-2.4.52-1.1.3.cpanel.x86_64 and a ea-apache24-2.4.52-1.1.1.cpanel.x86_64. Again, I'm going to assume that you are using ea-apache24-2.4.52-1.1.3.cpanel.x86_64 but if you are using ea-apache24-2.4.52-1.1.1.cpanel.x86_64 then note the difference in versions.
To get a list of the packages affected, you will need to grep through your yum.log. Now... probably your yum logs have already been rotated, so what you're after is likely in /var/log/yum.log-20211223 - but for simplicity sake I'm just going to look through all of the yum logs:
cat /var/log/yum.log* | grep 'ea-apache24.*2.4.52-1.1.3.cpanel' | awk '{print $5}' | sed s/-2.4.52-1.1.3.cpanel.*//g | sort | uniq
(again - note the RPM version used here)
This is a list of all of the packages you will want to downgrade. The | sort | uniq is there just in the off chance you have duplicate packages listed. You can either copy and paste this list into a package list passed to yum downgrade or you can pass the output of the above directly into the package list to yum downgrade:
yum downgrade $(cat /var/log/yum.log* | grep 'ea-apache24.*2.4.52-1.1.3.cpanel' | awk '{print $5}' | sed s/-2.4.52-1.1.3.cpanel.*//g | sort | uniq)
If you'll note in this particular case yum will tell you that you are about to downgrade all of these to 2.4.52-1.1.1. Proceed with this downgrade.
See what version of Apache you are using:
rpm -qa ea-apache24
This should report:
ea-apache24-2.4.52-1.1.1.cpanel.x86_64
If it happens to report:
ea-apache24-2.4.51-2.4.1.cpanel.x86_64
then you are done.
If it reports
ea-apache24-2.4.52-1.1.1.cpanel.x86_64
then do another downgrade:
yum downgrade $(cat /var/log/yum.log* | grep 'ea-apache24.*2.4.52-1.1.3.cpanel' | awk '{print $5}' | sed s/-2.4.52-1.1.3.cpanel.*//g | sort | uniq)
This time yum should report that it's going to downograde to 2.4.51-2.4.1. Proceed with this downgrade.
Now when you run:
rpm -qa ea-apache24
This should report:
ea-apache24-2.4.51-2.4.1.cpanel.x86_64
And that's it. You're now using Apache 2.4.51, which does not have this not responding bug.
However, ultimately, the folks over at Apache will need to fix this issue in Apache 2.4.52 or otherwise you won't get any of the benefits of Apache versions after 2.4.52.
