跨多个站点同步ASP.NET会话

Is there an elegant solution for synchronizing sessions across multiple ASP.NET applications? I'm sure this could easily be considered a security hole, but there is a 3rd party ASP.NET application involved, for which there is no ability to extend. For this reason, a second [related] site is being developed, but will require direct access to the sessions created on the 3rd party application.Is there an elegant solution for synchronizing