New GPUThor Rowhammer Defeats ECC on NVIDIA RTX A6000 to Gain Host Root Access
University of Toronto researchers present GPUThor, a Rowhammer attack that defeats ECC on NVIDIA RTX A4000-A6000 GDDR6 GPUs and achieves host root access.
GPUThor uses non-uniform hammering to bypass Target Row Refresh and overcome SECDED ECC on NVIDIA Ampere workstation GPUs with GDDR6 memory, inducing 72,000 to 377,552 bit flips per gigabyte across RTX A6000, A5000, A4500, and A4000 cards. Triple-bit silent data corruption enables host privilege escalation to root with the IOMMU enabled, reusing GPUBreach page-table corruption techniques, and double-bit DUEs allow escalation when the IOMMU is disabled during a ~10 ms lazy-service window. The attack cut end-to-end escalation time on the A6000 from 21.9 hours to 1.1 minutes. Reported to NVIDIA, Google, Microsoft, and AWS on April 29, 2026; findings were embargoed until August 25, 2026, and no CVE identifier was assigned.
- Affects RTX A6000, A5000, A4500, and A4000; no flips on GDDR6X, HBM2e, or newer GDDR6 parts
- RTX A5000 showed 377,552 flips per gigabyte, roughly 23,597 times GPUHammer's rate
- Requires ability to launch an unprivileged CUDA kernel on a shared or single-tenant GPU
- ECC-enabled A6000 produced one uncorrectable DUE roughly every two hours, aborting kernels
- Researchers advise avoiding cross-tenant GPU sharing and monitoring ECC error counters
- Vendors
- NVIDIAUniversity of Toronto
From the original article
6 min read at thehackernews.com
Academic researchers have disclosed a Rowhammer attack impacting NVIDIA workstation GPUs with GDDR6 memory that defeats error correction codes (ECC), the mitigation NVIDIA recommends against GPU Rowhammer, and enables denial-of-service (DoS) and privilege escalation to a root shell.
By @TheHackersNews · thehackernews.com
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