Linux Kernel EUVD-2026-86765

Requires the target system to have Arm Ethos-U NPU hardware with the accel/ethosu driver loaded, and the attacker must have local access to the accelerator device node to submit jobs. The specific trigger is a job that sets its SRAM size to 0 while its command stream still contains SRAM accesses; this causes the region base register write to be skipped so a stale base from a prior job is used. Impact is limited to SRAM regions and is most meaningful when the device is shared across multiple users or jobs. Limiting factors: local access only (not remotely reachable), authenticated device access required (PR:L), and dependency on niche Ethos-U hardware being present.

The NVD CVSS of 7.8 (AV:L/AC:L/PR:L/UI:N/C:H/I:H/A:H) is the standard Linux-kernel local memory-safety score, but it likely overstates real impact for this specific flaw. The vulnerability is deterministic (AC:L) and requires only local access to the Ethos-U accelerator device node (PR:L), with no user interaction. However, the actual damage is bounded to the NPU's SRAM region: when a job declares SRAM size 0 yet its command stream still references SRAM, the driver reuses a stale region base register from a prior job, causing NPU accesses to land in the previous job's SRAM area. This yields plausible cross-job data disclosure (reading another job's SRAM contents), cross-job corruption (writes to the wrong region), and hardware faults/crashes - not the full-system C:H/I:H/A:H the score implies. No EPSS score, no CISA KEV listing, and no public exploit are present. SSVC-style read: exploitation status is 'none observed', not automatable at scale (requires specific Arm Ethos-U hardware plus device access), and technical impact is partial. Net: not an urgent priority for the vast majority of environments - it matters only where Ethos-U NPUs are deployed and multiple users/jobs share the device. Note the CWE is unassigned (N/A) in the input; the class is effectively missing-validation leading to use of a stale hardware register.

A local user with access to the Ethos-U accelerator device submits an inference job that declares a SRAM size of 0 but includes SRAM read/write operations in its command stream. Because the region base register is not reprogrammed for a zero-size job, the NPU reuses the base address left over from a previously submitted job, allowing the attacker's job to read from or write into another job's SRAM region (or trigger a fault). No public proof-of-concept exists at the time of analysis, and exploitation requires the specific Arm Ethos-U NPU hardware plus local device access.