Zephyr Project up to 4.4.1 Flash Driver flash_sf32lb_mpi_qspi_nor.c flash_read/flash_write offset/size signed conversion

Summaryinfo

A vulnerability was found in Zephyr Project Zephyr up to 4.4.1 and classified as very critical. The affected element is the function flash_read/flash_write of the file drivers/flash/flash_sf32lb_mpi_qspi_nor.c of the component Flash Driver. Executing a manipulation of the argument offset/size can lead to signed conversion. This vulnerability appears as CVE-2026-11743. The attack requires local access. There is no available exploit.

Detailsinfo

A vulnerability classified as very critical was found in Zephyr Project Zephyr up to 4.4.1. This vulnerability affects the function flash_read/flash_write of the file drivers/flash/flash_sf32lb_mpi_qspi_nor.c of the component Flash Driver. The manipulation of the argument offset/size with an unknown input leads to a signed conversion vulnerability. The CWE definition for the vulnerability is CWE-195. The product uses a signed primitive and performs a cast to an unsigned primitive, which can produce an unexpected value if the value of the signed primitive can not be represented using an unsigned primitive. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

The SF32LB MPI QSPI NOR flash driver (drivers/flash/flash_sf32lb_mpi_qspi_nor.c) validated the flash offset and length on its read and write paths with the test (offset + size) > data->size. Because offset is a signed off_t while size is unsigned, a negative offset is converted to a large unsigned value and the addition can wrap to a small result that passes the check. The read path then performs memcpy(dst, (void *)(data->base + offset), size) and the write path programs flash at offset and cache-invalidates data->base + offset, in both cases accessing memory outside the mapped flash window. The driver's erase path already rejected negative offsets, but read and write did not. In builds with CONFIG_USERSPACE, flash_read and flash_write are syscalls whose verifiers validate the device object and the caller's buffer but deliberately delegate offset bounds checking to the driver. An unprivileged thread that has been granted access to this flash device can therefore call the syscall with a crafted negative offset and a buffer valid in its own memory domain, and reach the unchecked access. The most direct impact is on the read path: by choosing a negative offset and matching size, an attacker slides the memcpy source below the flash base and copies arbitrary CPU-addressable memory into its own buffer, disclosing memory it is not authorized to read. The write path additionally allows programming flash at an out-of-range address and invalidating an attacker-chosen cache range, affecting integrity and availability. Reachability requires userspace to be enabled and the raw flash device object to be granted to an untrusted thread. The fix replaces the check with qspi_nor_range_is_valid(), which rejects negative offsets and performs the bound comparison in overflow-safe 64-bit arithmetic on both paths, and additionally adds an SRAM DMA bounce buffer plus source/destination overlap rejection to prevent a separate DMA bus-hang condition.

The advisory is available at github.com. This vulnerability was named CVE-2026-11743 since 06/09/2026. The exploitation appears to be easy. Local access is required to approach this attack. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 08/07/2026).

Upgrading to version 4.4.2 eliminates this vulnerability. Applying the patch 909eb568750304d68ea481d1b56a489ae670bdae is able to eliminate this problem.

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Productinfo

Type

• Project Management Software

Vendor

• Zephyr Project

Name

• Zephyr

Version

• 4.4.0
• 4.4.1

CPE 2.3info

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CPE 2.2info

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