The subject of the present disclosure relates to compositions for dyeing or lightening human keratin fibers, comprising: (a) at least 25% by weight of at least one fatty substance (b) at least one amphoteric polymer (c) at least one basifying agent and (d) at least one oxidizing agent. The present disclosure also relates to a dyeing or lightening processes using the composition, and two- and three-compartment devices which make it possible to obtain a composition according to the present disclosure, after mixing of the compositions of the compartments just before application of the composition according to the present disclosure.
