The question is very short, so I'm not sure if this is related to a practical example or a general theoretical question, so I'll answer as if it's for the theoretical case:

This can be linked to the theory of thermodynamic equilibrium. Let's say the equilibrium potential of a redox couple is + 0.3 V. In that case, the net current should be zero, but the actual current is different. It is the sum of the cathodic and anodic currents flowing, which are both not zero, but the sum is zero.

Only if you go way above the equilibrium potential (e.g. + 0.7 V), the cathodic current will be zero. As long as you stay close to the equilibrium potential (e.g. + 0.35 V) of the redox couple, a cathodic current will still flow, albeit smaller than the anodic current, causing a net anodic current.

I included a small graphical overview in attachment.

I hope this is an answer to your question.

Following

The cathodic activation polarization(ηc)

ηc = bc Log (ic/io)