How to solve "sudo: /etc/sudoers.d is world writable"

Solution 1:

Run pkexec chmod 0755 /etc/sudoers.d

pkexec will use a different method of using root permissions, bypassing the issue.
And the chmod will fix the permissions.

Solution 2:

Run this 2 commands with (555) permissions:

pkexec chmod 555 /etc/sudoers
pkexec chmod 555 /etc/sudoers.d/README

Solution 3:

Did you try going into recovery mode and switching the permissions back to 775 for sudoers? I tried it and it worked.

1) Get into Ubuntu Recovery

2) Do mount -rw -o remount /

3) Then chmod 775 -R /etc/sudoers and chmod 775 -R /etc/sudoers.d/.

This time it should work.

4) Then do a sudo apt-get install of any package to test before you leave recovery mode. Late reply but I encountered the issue recently and tried this. It worked fine atleast for the world writable issue.