Not as rare as it should be (see https://cryptosense.com/blog/more-weak-rsa-keys-in-network-devices/ https://cryptosense.com/blog/more-weak-rsa-keys-in-network-

Not as rare as it should be (see https://cryptosense.com/blog/more-weak-rsa-keys-in-network-devices/ https://cryptosense.com/blog/more-weak-rsa-keys-in-network-d...) -- but there are much easier fixes than QKD.