A flaw was found in the way latest DDR4 DRAM chips implement Target Row Refresh (TRR) mitigation to prevent Rowhammer induced bit flips across memory space. An unprivileged system user may leverage this flaw and use Rowhammer attack variants to induce bit corruptions across memory space, potentially resulting in DoS OR privileges escalation scenarios.
This type of attack is different from the previously known (ex. CVE-2020-10255) by non-uniform patterns of memory access: means some patterns of memory access possibly allows to bypass current TRR defense of modern DDR4 chips.