Sim, eles são cumulativos.
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Update rollup packages are cumulative. For example, if you apply Update Rollup 4 on a computer that is running Exchange 2010, you receive all the fixes in that specific update package together with all the fixes that were released in all earlier update rollup packages. That is, in Update Rollup 4, you receive all the updates that were released in the previous Update Rollup 1 through Update Rollup 3 packages plus the updates in Update Rollup 4.