Given that the most common use of sudo is to give yourself root to run a command, and malware looking to elevate root can just rig up ~/.bashrc, what use is this patch? What use cases does it apply to and how common are they?
Sudo has much more fine-grained abilities for more surgical use-cases, like giving users the ability to only execute certain commands as a certain user, with detailed logging and auditing. It has a pretty involved config file (the pdf docu for it is 80 pages long), a plugin system, a seperate log format and log server, etc
I also believe those use-cases aren't that common anymore since multi-user systems fell out of favor. There is an argument that most of us could use a vastly simpler tool instead to reduce the attack surface. But that tool wouldn't be sudo, because sudo is built around supporting all these use cases.
The 'exploit' runs under the sysadmin's user. It gets there when the sysadmin inadvertently installs something malicious under their own user, or something they're running is exploited for example.
I also believe those use-cases aren't that common anymore since multi-user systems fell out of favor. There is an argument that most of us could use a vastly simpler tool instead to reduce the attack surface. But that tool wouldn't be sudo, because sudo is built around supporting all these use cases.