Non-Uniform Hammering Produces Up to 23,500x More Bit Flips on ECC-Protected NVIDIA GPUs

arXiv 2609.16546·medium signalXBlueskyLinkedInCopy link

GPUThor (arXiv 2609.16546, submitted 15 Sep 2026) reverse engineers GPU memory-access coalescing to build non-uniform Rowhammer patterns that activate aggressor rows harder than decoy rows, and identifies refresh instances to construct longer patterns that escape in-DRAM mitigations across refresh intervals. Prior GPU Rowhammer attacks triggered only tens to hundreds of bit flips; GPUThor yields 500x to 23,500x more across A4000, A4500, A5000, and A6000 cards, approaching state-of-the-art CPU Rowhammer flip rates. That closes the gap that made GPU Rowhammer impractical, which matters for anyone renting shared GPU capacity.