FAQ: I've found a bug in cPanel/WHM - who do I tell?
http://www.unofficial-support.com/node/61

The cPanel software is in constant development, and depending on what build is currently installed on your server (FAQ: What is the difference between BETA, DNSONLY, EDGE, CURRENT, RELEASE and STABLE builds?) you may find 'bugs' in the software.

As a quick definition, a bug is a programming error that causes a program to work poorly, produce incorrect results, or crash. (As an interesting aside, the term "bug" was coined when a real insect damaged one of the circuits of the first electronic digital computer, the ENIAC). A bug is different from a glitch, which refers to a hardware problem and not a software problem.

The cPanel team are using a piece of software called 'Bugzilla' to assist in their software development process - Bugzilla is a "Defect Tracking System" or "Bug-Tracking System". Defect Tracking Systems allow individual or groups of developers to keep track of outstanding bugs in their product effectively, and this is exactly how you can report back to cPanel any bugs that you might find.

-> http://www.unofficial-support.com/node/61