It's possible, but IMO it won't be easy to find. It's more likely we find exploit within CSPRNG/PRNG or someone put backdoor for k values of ECDSA.
How is it possible to backdoor 'k' value? I thought 'k' is generated from a hash of private key?
Not necessarily since it can be a random number inside (0
If there is a problem with implementation and you are not finding a random k and reuse the same value more than once, it is possible to calculate the private key from that.