In accordance with a first aspect of the present disclosure, a system is provided for applying patches to executable codes, comprising: a plurality of execution environments configured to execute said codes in different execution contexts; a control unit configured to apply the patches to said codes; wherein the control unit is configured to apply a specific patch to a specific code upon or after an execution environment configured to execute said specific code switches to an execution context corresponding to said specific code. In accordance with other aspects of the present disclosure, a corresponding method is conceived for applying patches to executable codes, and a corresponding computer program is provided.