PCT claiming priority of CIP

PCT does not really recognize any priority between a CIP and an original/parent application as is done in the US - they go strictly by publication dates. So, since your CIP application was obviously filed before the publication of the original or parent US application, and since the PCT application claims priority to the US CIP, the original/parent US application will not constitute prior art against your PCT application. Sometimes, practitioners inadvertently claim something in a PCT application that is based upon, for example, one or more CIP applications but forget the fact that while the continuity/priority may hold up in the corresponding US application, if there is no direct priority back to a particular US application, and that US application is published, then that published application could serve as prior art against your later-filed application. In your case, since there has been no publication yet of any of the applications, your priority is intact and the original/parent US application will not constitute prior art.

Steven, there is more to that outside the US. PCT priority rules are based on the Paris Convention. You can only claim priority on a FIRST patent application. A CIP is necessarily a second or subsequent application, so the priority claim based on the CIP is invalid, UNLESS the PCT is directed exclusively to the new matter that was added in the CIP. Since the PCT was filed more than 12 months after the initial US application, the priority claim cannot be rectified to be based on the initial US application.

In summary, the priority claim being invalid, anything published before the filing of the PCT application, even by the inventors themselves is prior art against the PCT application. If the publication of the initial US application is the first publication of the invention, the PCT application may still survive, but you need to hope that no other prior art was published up to the filing date of the PCT.

I agree with Jean Jaques, Article 4 C. (2) of the Paris Convention is the respective legal basis. As the utility application has already served as a basis for a priority claim (for the CIP), simply withdrawing the utility application may not improve your situation (see: Articel 4 C. (4) Paris Convention).
http://www.wipo.int/treaties/en/text.jsp?file_id=288514#P83_6610

With all due respect Steven, Jean Jacques, Benjamin, I have to differ. The claim to priority is valid (claim to the first patent application means the first application in which that invention with its CIP limitations was disclosed) - it simply means that your PCT is imputed the date of the CIP. Therefore any earlier application that gets published (in this case the parent) will be prior art.
Remember that the PCT is a placeholder for subsequent nationally and regionally prosecuted patent applications. Those jurisdictions will look at the prior art available prior to the CIP date (since your PCT claimed priority from the CIP). Therefore it comes down to the claim language. Insofar as your claims are novel and inventive/non-obvious over the parent case (in other words the limitations provided by the CIP are not obvious in light of the published parent case), your claims should be allowed in subsequent national and regional applications.