CCA on PKCS#5 using error feedback
Ok, suppose that we have a ciphertext $(c_1, c_2, ..., c_8)$ that we wish to decrypt.

What we start off with is to make a guess for $p_8$, which is the decryption of the last byte of the block.  Suppose that we guess that it is 0x07; we then need to validate that guess.

What we do is create a two block message; the second block is the challenge ciphertext block $(c_1, c_2, ..., c_8)$; the first block has 7 random bytes; followed by $0x07 \oplus 0x01 = 0x06$.  We then send it to the Oracle for decryption.

Let us recall when CBC mode decryption is; it is $P_i = C_{i-1} \oplus D_k( C_i )$.  In the specific case of the last block, what the decryption process will do is first internally decrypt the last ciphertext block $(c_1, c_2, ..., c_8)$, and get the plaintext block $(p_1, p_2, ..., p_8)$; it'll then exclusive or that with the previous ciphertext block; the last byte of that result will be $p_8 \oplus 0x06$ (because we made the last byte of the next-to-last-block 0x06).

Now, if our guess was correct; that is $p_8 = 0x07$, the result of this exclusive-or is $0x07 \oplus 0x06 = 0x01$; a last block with the last byte of 0x01 is valid padding, and so the message will be accepted.

On the other hand, if our guess was not correct, then the result of this exclusive-or is something other than 0x01.  Now, it's possible that the result will also look like a valid padding (for example, the last three bytes might be 0x03 0x03 0x03), however that would also involve other bytes (which we set randomly), and so that's unlikely.

So, to actually perform this attack, we would make guesses at $p_8$, and send out ciphertexts to test those guesses.  And, once we have determined the likely value of $p_8$, we can start guessing $p_7$ (which works just the same way, except we're targetting the $0x02$ $0x02$ final pattern).

BTW: the Bliechenbacker CCA attack is actually unrelated.