Can you explain a bit more what you mean by "secure" in the context of "actual revocations"? The oxymoronic nature isn't self-evident enough for me to catch your intended meaning before my first cup of coffee.
If you receive a forged crl, in the worst case it will revoke certificates that you can't trust anyway. Even if it says "certificate X is still good", that's equivalent to receiving no crl.
If you receive a forged crl, in the worst case it will revoke certificates that you can't trust anyway. Even if it says "certificate X is still good", that's equivalent to receiving no crl.