CVE-2025-21656 hwmon: (drivetemp) Fix driver producing garbage data when SCSI errors occur
The Linux kernel drivetemp driver may expose uninitialized memory to userspace when SCSI errors occur, allowing local attackers to read sensitive data.
- 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-2025-21656?
CVE-2025-21656 is a medium-severity vulnerability in Linux kernel, published on 21 Jan 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:
hwmon: (drivetemp) Fix driver producing garbage data when SCSI errors occur
scsi_execute_cmd() function can return both negative (linux codes) and positive (scsi_cmnd result field) error codes.
Currently the driver just passes error codes of scsi_execute_cmd() to hwmon core, which is incorrect because hwmon only checks for negative error codes. This leads to hwmon reporting uninitialized data to userspace in case of SCSI errors (for example if the disk drive was disconnected).
This patch checks scsi_execute_cmd() output and returns -EIO if it's error code is positive.
[groeck: Avoid inline variable declaration for portability]
Which versions are affected by CVE-2025-21656?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-21656?
Apply the vendor's patch.
Is CVE-2025-21656 being exploited?
There is no known exploitation of CVE-2025-21656 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-21656, DEBIAN-CVE-2025-21656, GHSA-2g47-jxc2-73xh, ROOT-OS-DEBIAN-11-CVE-2025-21656, ROOT-OS-DEBIAN-12-CVE-2025-21656, ROOT-OS-UBUNTU-2204-CVE-2025-21656 and 1 more.