Linux Kernel CVE-2026-98143

Requires the ARM Ethos-U accelerator (accel/ethos-u) driver to be present and bound to Ethos-U65 hardware - a niche configuration limited to specific embedded SoCs such as NXP i.MX93. The attacker needs local access to the accelerator character device and the ability to submit NPU command streams (CMDSTREAM_BO_CREATE). Triggering the corruption path specifically requires a U65 stream using truncating rounding (value 1), which routes to the two-tile address path and derives a feature-map size from tile bases the stream never initialized; U65 natural rounding (value 2) only produces the -EINVAL functional failure. Limiting factors: local-only vector, requires accel-device access (PR:L), U85 hardware is unaffected, and the driver must be built and running against real U65 silicon - not a default configuration on general-purpose systems.

This is a HIGH-CVSS-but-LOW-real-risk issue. NVD scores it 7.8 via CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H, but the CVSS impact triad (C:H/I:H/A:H) is overstated relative to the actual defect. The described behavior is fundamentally a register-field misinterpretation: on ARM Ethos-U65 NPUs, bits 15:14 of NPU_SET_{IFM,OFM}_PRECISION encode the rounding mode, but the command-stream parser always read them as the U85 storage mode. The dominant real-world effect is a functional regression - legitimate U65 command streams requesting natural rounding are rejected with -EINVAL (72 Teflon test-suite failures on i.MX93), which is availability/usability, not confidentiality. The genuine security-relevant path is the truncating-rounding misread selecting a two-tile address path and computing a bogus feature-map size from tile bases the stream never set, which is a memory-corruption/OOB risk (crash-dominant DoS, not information disclosure). There is no EPSS score, no CISA KEV listing, and no public exploit identified. SIGNAL CONFLICT: the input Tags say 'Information Disclosure' (implying C:H), but the description and patch indicate a functional/corruption bug with no read primitive - C:H is not supported. The CVSS AV:L/PR:L is consistent with the description (local access to the accel device is required). Overall: low priority outside the specific embedded ML deployments that run this driver.

A local user with access to the ARM Ethos-U accelerator device on an i.MX93-class SoC submits a crafted NPU command stream using U65 truncating rounding, causing the parser to take the two-tile address path and compute a bogus feature-map size from uninitialized tile bases, leading to memory corruption or a kernel crash. No public exploit code exists, and exploitation requires local access plus the ability to submit command streams to the accel device.