The specific heat C(B,T) of an YBa 2 Cu 3 O 7.00 single crystal is measured from 1.2 to 10K in magnetic fields up to 14T. The anisotropic component C aniso (T,B)≡C(T,B‖c)−C(T,B⊥c) is a pure vortex quantity. Our data suggest that the electronic density of state (DOS) due to the vortices peaks at E=E F , a very unusual behaviour. This result, necessary for thermodynamic considerations, agrees with a recent d-wave calculation. Moreover, this model predicts a scaling relation that is followed by our data. Our experimental range corresponds to a crossover region where the limit C aniso (T,B)∝TB 1/2 used in former works does not strictly apply.