Does one have to list all publications on a CV? Some years ago, I published some papers that I'm not particularly proud of. They aren't in prestigious or widely known venues in my field, and I'm sure that few if any people in my field have seen these papers. When I apply for a job, am I permitted to omit these publications from my CV? Or am I, for some reason, obligated to list all prior publications?
If the CV is for job applications, you can certainly omit publications.  If you omit a lot of publications, you might want to title your publication list "Selected Publications".

If the CV is for a grant application or a promotion, there may be more specific rules about what can and cannot be included, so you should check those.