GPUThor Attack Bypasses ECC on NVIDIA GPUs for Root Access

Researchers from the University of Toronto have revealed a new Rowhammer attack named GPUThor that can bypass ECC protections on NVIDIA GPUs, specifically targeting Ampere-class models like the RTX A4000 and A6000. This attack allows for denial-of-service (DoS) and root-level privilege escalation by corrupting GPU page tables, enabling unauthorized memory access. GPUThor achieves significantly higher bit-flip rates than previous attacks, generating between 72,000 and 377,000 flips per GB, which is 4,548 to 23,597 times higher than the earlier GPUHammer method. The attack can induce a DoS state, causing the GPU to reset and terminate workloads. The researchers noted that even with ECC enabled, GPUThor can generate double-bit errors that ECC detects but cannot correct, leading to data corruption. The implications for AI model training are severe, as successful attacks could compromise model accuracy. The attack details were published on August 26, 2026, and have raised significant concerns among users of affected NVIDIA GPUs.

Key Points: • GPUThor bypasses ECC protections on NVIDIA Ampere-class GPUs. • The attack allows for DoS and root-level privilege escalation. • Bit-flip rates achieved by GPUThor are significantly higher than previous Rowhammer attacks.