GPUThor Rowhammer Bypasses ECC on NVIDIA Ampere GPUs for Potential Host Root Access

University of Toronto researchers disclosed GPUThor, a GPU-based Rowhammer technique that can bypass practical protections provided by SECDED ECC on certain NVIDIA Ampere workstation GPUs using GDDR6 memory, including the RTX A6000. By using a non-uniform memory-hammering pattern that accounts for undocumented request coalescing and Target Row Refresh behavior, the technique substantially increases bit-flip rates and can trigger uncorrectable double-bit errors or incorrect repair of triple-bit errors.

An attacker needs to execute an unprivileged CUDA kernel, creating risk in shared GPU-tenancy environments and from untrusted local GPU workloads. The researchers demonstrated data corruption and GPU denial of service and described a path to host root privilege escalation through GPU page-table corruption. NVIDIA recommends enabling System-Level ECC (SYS-ECC), enforcing IOMMU/DMA isolation, monitoring GPU ECC telemetry, and restricting untrusted or cross-tenant GPU workloads; no CVE, patch, or confirmed in-the-wild exploitation was reported.