A server, processing device and/or processor includes a processing core and a memory controller, operatively coupled to the processing core, to access data in an off-chip memory. A memory encryption engine (MEE) may be operatively coupled to the memory controller and the off-chip memory. The MEE may store non-MEE metadata bits within a modified version line corresponding to ones of a plurality of data lines stored in a protected region of the off-chip memory, compute an embedded message authentication code (eMAC) using the modified version line, and detect an attempt to modify one of the non-MEE metadata bits by using the eMAC within a MEE tree walk to authenticate access to the plurality of data lines. The non-MEE metadata bits may store coherence bits that track changes to a cache line in a remote socket, poison bits that track error containment within the data lines, and possibly other metadata bits.