Infinitely many supersingular primes for some Mumford's abelian fourfolds

Elkies proved the infinitude of supersingular primes for elliptic curves over real number fields. We generalize Elkies’ result to some abelian fourfolds in Mumford’s families, and more generally, to certain families of Kuga-Satake abelian varieties. The proof relies on the study of local deformation spaces at closed points of the integral model of a Hodge-type Shimura variety, based on the work of Madapusi, and on the analysis of real points of a Shimura curve, based on the work of Shimura.