Chipmaker Patch Tuesday: Nvidia, AMD, Arm Issue Security Advisories
AMD, Arm, and Nvidia issued Patch Tuesday advisories fixing a Linux GPU driver DoS flaw, nine Mali GPU vulnerabilities, and two high-severity Triton defects.
AMD fixed CVE-2026-43603, a NULL pointer dereference in its Linux GPU kernel driver that can crash systems and cause denial-of-service, credited to SecMate researchers, with patches for EPYC, Ryzen, Radeon, and Instinct shipped in July and embedded variants due in October. Arm published an advisory covering nine Mali GPU vulnerabilities allowing use-after-free access, kernel information leaks, or DoS, releasing fixes for Valhall and 5th Gen GPU Architecture drivers, with Bifrost also affected. Nvidia updated Triton Inference Server for Linux to resolve two high-severity flaws, one causing DoS and one enabling information disclosure, data tampering, and DoS. Intel had issued no new advisories since the previous Patch Tuesday.
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.
Redtail Payload Analysis [Guest Diary], (Wed, Sep 9th)
SANS guest analyst detonated a RedTail Linux sample from a DShield honeypot, finding process masquerading as php-fpm, monitoring-kill behavior, and a TCP listener.
A DShield honeypot captured multi-architecture RedTail Linux executables (ARM, ARM64, i686, RISC-V, x86-64) deployed via shell scripts. Dynamic analysis of the UPX-packed, statically linked x86-64 sample (SHA-256 63be5f38...d35e) in an isolated Ubuntu 24.04 VM on Proxmox showed it renamed its process via prctl(PR_SET_NAME), killed a filesystem-monitoring process, and opened a TCP listening socket while surviving processes posed as php-fpm or PostgreSQL-like workers. Differential memory images pre- and post-execution were captured from the hypervisor for forensics.
Building a Linux GPU Driver for the M4 Mac Mini in One Month
Two developers built a fully OpenGL ES 3.0 compliant Linux GPU driver for the M4 Mac Mini in one month via clean-room reverse engineering.
Niklas and the author reverse engineered Apple's AGX GPU firmware ABI and user-space components in about a month, a process that normally takes years, producing an OpenGL ES 3.0 conformant driver fast enough to run Minecraft at 200fps on an M4 Mac Mini. The work was done transparently using hypervisor traces without examining Apple binaries, following clean-room practices, and included a custom shader compiler, command stream builder, and a full Linux kernel driver for the firmware ABI. The A18 Pro firmware ABI proved significantly more complex than the M1's, with 1.5x as many structs and twice as many pointers. All experiments and provenance evidence were published in public agx-re repositories.
USN-8729-1: Linux kernel vulnerabilities
Ubuntu issued USN-8729-1 fixing Linux kernel vulnerabilities across ARM, Bluetooth, GPU, SCSI, SMB, and Azure MANA subsystems.
Ubuntu released USN-8729-1 addressing several security issues discovered in the Linux kernel that could allow an attacker to compromise the system. Fixes span ARM32/ARM64/PowerPC architectures, Bluetooth, GPU, InfiniBand, and network drivers, plus the Microsoft Azure Network Adapter (MANA) driver. The update also corrects flaws in the SCSI and SPI subsystems, SMB and NTFS3 file systems, EFI core, and file systems infrastructure.