Researchers at the University of Toronto have unveiled a new rowhammer variant named GPUBreach that sidesteps IOMMU defenses on GDDR6‑based NVIDIA GPUs. Earlier attacks like GDDRHammer relied on disabling IOMMU to reach memory, but this technique corrupts driver metadata within the buffers the IOMMU does allow, opening a path to code execution. The exploit works from the CPU side, avoiding GPU DMA.

By targeting memory‑safe bugs in the GPU driver, GPUBreach manipulates the metadata of IOMMU‑approved buffers, causing the kernel‑privileged driver to perform out‑of‑band writes. Because the driver is trusted by the OS, those writes escape the IOMMU’s address checks, granting the attacker root privileges. ECC on GDDR6 mitigates some flips, but it cannot stop the metadata corruption in modern server environments and workstations.

NVIDIA received the GPUBreach details in November 2025 and has warned cloud providers such as Google, AWS and Microsoft. While upcoming cards equipped with GDDR7 or HBM3/4 memory are immune, legacy GDDR6 GPUs in data‑centers and high‑end workstations remain at risk until firmware patches arrive. Administrators should audit driver versions and consider retiring vulnerable hardware as part of a comprehensive security strategy.