IceCube has observed a flux of cosmic neutrinos, with a bump in the energy range $10 lesssim E/{rm TeV} lesssim 100$ that creates a $3sigma$ tension with gamma-ray data from the Fermi satellite. This has been interpreted as evidence for a population of hidden cosmic-ray accelerators. We propose an alternative explanation of this conundrum on the basis of cold dark matter which decays into sterile neutrinos that after oscillations produce the bump in the cosmic neutrino spectrum.