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   GPUThor attack defeats NVIDIA ECC protection for root access

   bleepingcomputer.com · 48d ago · August 26th, 2026

   A newly disclosed Rowhammer attack called GPUThor can bypass error-correcting code (ECC) protections on NVIDIA GPUs, enabling denial-of-service (DoS) and root-level privilege escalation. In a paper published by the University of Toronto, researchers say that GPUThor achieves far more practical bit-flip rates than past concepts like their own GPUHammer or GPUBreach , which became irrelevant after ECC was introduced. The attack was demonstrated against Ampere-class NVIDIA workstation GPUs with GDDR6 memory, including the RTX A4000, RTX A4500, RTX A5000, and RTX A6000, all widely used in AI and cloud infrastructure. GPUThor attack improvement Rowhammer is the name for a class of attacks where memory rows are repeatedly accessed (“hammered”) in a way that increases the likelihood of bits in neighboring memory regions to flip, changing their state from one to zero or vice versa. This can lead to data corruption and security risks. Since AI model training relies heavily on GPU power, a successful Rowhammer attack could have a devastating impact on the model's accuracy. To mitigate risks from this type of attack, NVIDIA uses mitigations such as SECDED ECC to correct single-bit errors and detect double-bit errors within monitored memory blocks. However, University of Toronto researchers adjusted GPUThor so its hammering follows a non-uniform pattern at a rate that avoids activating GDDR6’s Target Row Refresh (TRR) mitigations. Specific hammering pattern used by GPUThor Source: Univer