CBC is vulnerable to error oracles if you don't encrypt-then-MAC it properly (without the MAC it's also malleable, which is a game-over flaw). GCM is vulnerable to a bunch of its own misuse issues; it doesn't "use" random nonces, it is conceivably (through not really realistically) unsafe to use random nonces, and if you screw up nonce handling it blows up worse than CBC does.

My point is just, these things all have rough edges.