CVE-2025-39788 scsi: ufs: exynos: Fix programming of HCI_UTRL_NEXUS_TYPE
An integer overflow in the Exynos UFS driver causes undefined behavior and potential denial of service on Google gs101 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-2025-39788?
CVE-2025-39788 is a high-severity vulnerability in Debian Debian Linux, published on 11 Sep 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:
scsi: ufs: exynos: Fix programming of HCI_UTRL_NEXUS_TYPE
On Google gs101, the number of UTP transfer request slots (nutrs) is 32, and in this case the driver ends up programming the UTRL_NEXUS_TYPE incorrectly as 0.
This is because the left hand side of the shift is 1, which is of type int, i.e. 31 bits wide. Shifting by more than that width results in undefined behaviour.
Fix this by switching to the BIT() macro, which applies correct type casting as required. This ensures the correct value is written to UTRL_NEXUS_TYPE (0xffffffff on gs101), and it also fixes a UBSAN shift warning:
UBSAN: shift-out-of-bounds in drivers/ufs/host/ufs-exynos.c:1113:21 shift exponent 32 is too large for 32-bit type 'int'
For consistency, apply the same change to the nutmrs / UTMRL_NEXUS_TYPE write.
Weakness: CWE-787
Which versions are affected by CVE-2025-39788?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-39788?
Apply the vendor's patch.
Is CVE-2025-39788 being exploited?
There is no known exploitation of CVE-2025-39788 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as BELL-CVE-2025-39788, DEBIAN-CVE-2025-39788, GHSA-44fw-3x9p-jf29, ROOT-OS-DEBIAN-11-CVE-2025-39788, ROOT-OS-DEBIAN-12-CVE-2025-39788, ROOT-OS-DEBIAN-13-CVE-2025-39788 and 3 more.