By using the Planck map of the cosmic microwave background (CMB) radiation, we have checked and confirmed the existence of a correlation between supernova (SN) redshifts, z_SN_, and CMB temperature fluctuations at the SNe locations, T_SN_, which we previously reported for the Wilkinson Microwave Anisotropy Probe data. The Pearson correlation coefficient for the Planck data is r=+0.38+/-0.08, which indicates that the correlation is statistically significant (the signal is about 5{sigma} above the noise level). The correlation becomes even stronger for the Type Ia subsample of SNe, r_Ia_=+0.45+/-0.09, whereas for the rest of the SNe it is vanishing. By checking the slopes of the regression lines T_SN_/z_SN_ for Planck's different frequency bands, we have also excluded the possibility of this anomaly being caused by the Sunyaev-Zeldovich effect. The remaining possibility is some, unaccounted for, contribution to the CMB from distant (z>0.3) foreground through either the integrated Sachs-Wolfe effect or thermal emission from intergalactic matter.