  We present a dark sector model addressing both the Hubble tension and the
core-cusp problem. The model is based on a hidden Abelian gauge symmetry group
with some chiral fermions required by the anomaly cancellation conditions,
producing a candidate for the decaying fermion dark matter as a solution to the
Hubble tension. Moreover, the sub-keV mass regime and the thermal history of
the dark sector help the dark matter candidate resolve the core-cusp problem
occurring in the standard $\Lambda$CDM cosmology.
