As far as I know apple does not publish that information until they implement a fix in an update. At that point they publish what the bug is and how the update plans on fixing the bug.
If Apple published a list of their bugs in the OS, hackers could take advantage of the bug. Only in rare cases are bugs published, but never by OS suppliers. The bugs are published by security firms when the bug is so dangerous the public needs to know of its existence to avoid being hacked.
Most issues with mac are not bugs in the OS but problems due to slight differences between the OS X series. This issue is especially noticeable when compiling code from MacPorts.