CVE-2026-53172

What it actually does

This is a Linux kernel memory-corruption flaw in the Arm Ethos-U NPU accelerator driver command stream parser. The vulnerable code extracts an input feature map region index using a 0x7f mask, allowing values up to 127, while the backing arrays are sized for only 8 regions. A local userspace caller that can submit a crafted Ethos-U command stream can cause an out-of-bounds write into adjacent kernel heap memory. Depending on kernel configuration, heap layout, and device exposure, the result may be kernel crash, denial of service, or potentially local privilege escalation through controlled kernel memory corruption.

Why it matters to the business

Systems that expose the affected Ethos-U NPU driver to local workloads could be destabilized or, in a worst case, allow a local attacker or compromised application to gain higher privileges on the host. This is most relevant to Linux-based embedded, edge, IoT, and AI inference devices using Ethos-U acceleration. The currently reported EPSS is low, it is not listed in CISA KEV, and no public exploit maturity is indicated, so the near-term mass-exploitation risk appears low; however, kernel memory corruption in device drivers should still be treated as high-value hardening work where the driver is enabled.

How an attack unfolds

An attacker first needs local ability to interact with the vulnerable Ethos-U accelerator interface, typically through a userspace component or device node that submits command streams to the kernel driver. The attacker crafts a command stream containing NPU_SET_IFM_REGION with a parameter whose low 7 bits produce a region value greater than 7. Because the vulnerable parser accepts that larger value, later validation and size-calculation routines use it directly as an array index into fields allocated for only 8 entries. This causes a write beyond the intended array into neighboring kernel heap data. A simple exploit may crash the kernel and cause a denial of service; a more advanced exploit would attempt to shape heap allocations and overwrite useful kernel data to gain elevated privileges. No named threat actors or active exploitation are currently reported for this issue.

How to fix it

Apply a kernel update from the Linux distribution, device vendor, or BSP maintainer that includes the fix changing the IFM region mask from 0x7f to 0x7, matching the other region assignments. If no packaged fixed version is available, backport the upstream kernel patch for accel/ethosu command stream parsing. As interim mitigation, disable or unload the Ethos-U driver where it is not required, remove access to the related device node from untrusted users and containers, and restrict NPU command submission to trusted service accounts only. On embedded devices, prioritize patched firmware or kernel images from the OEM or silicon vendor.

How to confirm the fix worked

Confirm the running kernel includes the patched Ethos-U driver source or vendor advisory fix. Where source or debug symbols are available, verify NPU_SET_IFM_REGION applies a 0x7 mask rather than a 0x7f mask. Confirm the affected driver is not loaded or the device node is not exposed on systems that do not require Ethos-U acceleration. Validate access controls on any Ethos-U device interface so untrusted local users, containers, or sandboxed applications cannot submit arbitrary command streams. After patching, run regression tests for NPU workloads and monitor kernel logs for crashes or sanitizer findings involving the ethosu driver.

Typical attack path

1. Gain local code execution on a Linux system where the vulnerable Ethos-U NPU driver is present and accessible.
2. Open or otherwise reach the userspace interface used to submit Ethos-U command streams.
3. Construct a malicious command stream containing NPU_SET_IFM_REGION with a region parameter greater than 7.
4. Submit the command stream to the kernel driver for validation/parsing.
5. Trigger out-of-bounds writes in the kernel heap when the invalid region index is used as an array subscript.
6. Cause a kernel crash or attempt further heap manipulation to achieve privilege escalation.

How to detect it

There is no reliable single log entry proving exploitation because the bug is a kernel heap memory-corruption condition and successful exploitation may leave minimal artifacts. Review kernel logs, persistent journal entries, crash dumps, and device telemetry for oopses, panics, KASAN reports, slab corruption, or general protection faults involving the Ethos-U driver or NPU command stream handling. Correlate crashes with local process execution, container activity, or applications that opened the Ethos-U device interface shortly before the event. On systems with auditd or eBPF telemetry, search for untrusted processes opening Ethos-U-related device nodes and issuing ioctl-heavy activity before kernel instability. Forensic review should include kernel crash dumps, loaded module lists, device-node permissions, and recent firmware/kernel changes. Because no active exploitation or public exploit is reported, absence of these artifacts is not conclusive, but repeated ethosu-adjacent crashes are suspicious.

• ethosu
• /dev/ethosu
• NPU_SET_IFM_REGION
• slab-out-of-bounds
• KASAN: slab-out-of-bounds
• BUG: KASAN
• general protection fault
• kernel BUG
• Oops:
• Unable to handle kernel
• accel/ethosu
• ethosu_ioctl
• ethosu_buffer
• ethosu_network
• ethosu_mailbox

What your security team should do

• Inventory Linux systems, embedded devices, edge appliances, and AI inference platforms using Arm Ethos-U acceleration or the Linux accel/ethosu driver.
• Prioritize patching devices where local untrusted code, containers, third-party applications, or multi-tenant workloads can access the NPU interface.
• If patching is delayed, disable the Ethos-U driver or restrict permissions on the device interface to only trusted workloads.
• Ask device vendors and BSP maintainers for kernel or firmware releases containing the accel/ethosu IFM region index bounds fix.
• Add monitoring for kernel crashes, KASAN reports, and oops messages referencing ethosu, slab out-of-bounds, or command stream parsing.
• Treat unexplained kernel crashes on affected NPU-enabled devices as potential exploitation until logs and workload history are reviewed.