The technology disclosed relates to thwarting attempts in between software releases to take advantage of security holes in web applications. A virtual patch is a data object comprising an identifier that indicates a relevant local context for the patch and may be created while the application is running. One or more conditions included in the patch are evaluated using data from a service request or from the local context. A patch directive specifies an action to perform when the one or more conditions are satisfied. A virtual patch may be applied to the running application without requiring replacing the application code. Responsive to a request for a web service, a web application may execute code in multiple distinct local contexts such as session management, authorization, and application-specific business logic. The code for each local context may independently retrieve a set of virtual patches relevant to its particular local context.