  Recently, it has been shown that cosmic neutrino flux at the GRB/AGN source,
$F_{\nu_e}^0 : F_{\nu_{\mu}}^0 : F_{\nu_{\tau}}^0 \simeq 1 :2 :0 $, inevitably
oscillates (in the three neutrino framework) to 1 : 1: 1, irrespective of the
mixing angle relevant to the solar data. It has also been pointed out that the
intrinsic flux of the cosmic high-energy neutrinos may not have the standard
ratio, in which case the cosmic neutrino flux in the far distance should be
dependent of the mixing angle. For neutrinos with nonzero electromagnetic
properties, we show in the latter case that matter effects on oscillations of
high-energy cosmic neutrinos can substantially modify the vacuum oscillation
probability, if the mass-squared difference is $\lsim 10^{-10}$ eV^2.
