2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/89435We suggest an attack on a symmetric non-ideal quantum coin-tossing protocol suggested by Mayers Salvail and Chiba-Kohno. The analysis of the attack shows that the protocol is insecure.11 pages 1 figure,equations (29) and (30) changedQuantum Physicstext