CVE-2026-11743 Missing negative-offset/overflow check in SF32LB MPI QSPI NOR flash driver allows out-of-bounds read and write
An integer overflow in the Zephyr RTOS QSPI NOR flash driver allows unprivileged users to read arbitrary memory and modify flash contents.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-11743?
CVE-2026-11743 is a medium-severity vulnerability in zephyrproject zephyr, published on 7 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Weakness: CWE-125
Which versions are affected by CVE-2026-11743?
How do I fix CVE-2026-11743?
No fix has been published for CVE-2026-11743 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-11743 being exploited?
There is no known exploitation of CVE-2026-11743 in the wild and no public exploit code.
Sources
Also known as GHSA-c6wh-gwg4-fj5j.