$CP$ violation in neutral kaon mixing in $D^0\to K_S{K}_S$

We study CP violation induced by neutral kaon mixing in $a_{CP}(D^0\to K_S{K}_S)$. We show that the contribution from neutral kaon mixing arises only in connection with second-order weak interactions in $D$ decays. We estimate this effect to be at the ${10}^{-6}$ level, and thus negligible compared to current experimental sensitivity and to the expected contribution from CP violation in the charm sector.