CVE-2025-39921 spi: microchip-core-qspi: stop checking viability of op->max_freq in supports_op callback
A division by zero in the Microchip Core QSPI driver causes probe failure, leading to denial of service for attached memory devices.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-39921?
CVE-2025-39921 is a medium-severity vulnerability in Linux kernel, published on 1 Oct 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
spi: microchip-core-qspi: stop checking viability of op->max_freq in supports_op callback
In commit 13529647743d9 ("spi: microchip-core-qspi: Support per spi-mem operation frequency switches") the logic for checking the viability of op->max_freq in mchp_coreqspi_setup_clock() was copied into mchp_coreqspi_supports_op(). Unfortunately, op->max_freq is not valid when this function is called during probe but is instead zero. Accordingly, baud_rate_val is calculated to be INT_MAX due to division by zero, causing probe of the attached memory device to fail.
Seemingly spi-microchip-core-qspi was the only driver that had such a modification made to its supports_op callback when the per_op_freq capability was added, so just remove it to restore prior functionality.
Which versions are affected by CVE-2025-39921?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-39921?
Apply the vendor's patch.
Is CVE-2025-39921 being exploited?
There is no known exploitation of CVE-2025-39921 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-39921, DEBIAN-CVE-2025-39921, GHSA-6595-xfjg-wffj, UBUNTU-CVE-2025-39921.