CBC mode with same plaintext
the key and plaintext is the same. The attacker knows this and the IVs used but doesn't know the plaintext. Is there anything to learn about the plaintext when multiple ciphertexts are available instead of only one?


No. Giving the attacker multiple encryptions of a single plaintext using a randomly chosen IV and a fixed key with AES-CBC does not leak any more information about the plaintext than does a single ciphertext.

In fact if the attacker didn't know whether or not they were the same plaintext (but had the same length), the attacker couldn't tell you whether or not they encrypted the same plaintext.