GPUThor breaks the error correction Nvidia recommended against Rowhammer

GPUThor, a new Rowhammer attack from the University of Toronto, defeats Nvidia’s recommended ECC on Ampere GPUs (RTX A4000, A4500, A5000, A6000) by hammering rows with non-uniform patterns that synchronize with Target Row Refresh, producing 500–23,500 times more bit flips than prior GPU attacks. The technique forces rapid double-bit errors that ECC cannot correct, enabling denial-of-service, root-shell takeover via corrupted page tables, and silent data corruption on ECC-protected cards.