The present invention relates to a heat exchanger for controlling the temperature of a first fluid using a second fluid, wherein the heat exchanger has a base for separating the first fluid from the second fluid, said base having a sealing region. Furthermore, the heat exchanger has a partition for separating the first fluid from the second fluid, wherein the at least one partition is connected in a fluid-tight manner to the base, wherein the at least one partition forms a fluid duct for the first fluid. Furthermore, the heat exchanger has a housing. In the sealing region between the base and the housing, there is arranged a sealing element which is pressed in a fluid-tight manner against the base and against the housing.