What is the probability of un-authenticated messages to go through CCM because of channel errors? Consider having the worst possible communications channel, where bits are flipped with probability 0.5. 

Is there any probability that channel errors make the change in a frame go un-detected through CBC-MAC?
Is there any probability that channel errors make the change in a frame go un-detected through CBC-MAC?

For any Message Authentication Code, there is always a probability [1] that the modified message will just happen to verify against the modified tag.
In your extreme &quot;worse possible case&quot; scenario, it's quite simple to compute; your communication channel effectively replaces the message/tag with a completely random message/tag.  And, if we compute the MAC on a random message, the probability that it matches a random tag is $2^{-32}$ for a 32 bit tag.

[1]: Unless the errors are tightly constrained.  For example, with CBC-MAC with a full length tag, we will always detect any error if the error is constrained to be always within one block, with all the other blocks being transmitted correctly.  However, random errors (and active attackers) are generally not so accommodating with how they modify the message.