CVE-2025-21656 [Medium] | Security Vulnerability in Linux Kernel

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]

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.03%	0.19%	+0.16%
2	2025-11-21	0.06%	0.03%	-0.03%
3	2025-11-18	—	0.06%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.03%

0.19%

+0.16%

2025-11-21

0.06%

0.03%

-0.03%

2025-11-18

—

0.06%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
5.5	3.1	MEDIUM	`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H` Click to expand Attack vector (AV:L) They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	1.8	3.6	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

5.5

3.1

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Click to expand

Attack vector (AV:L): They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L): A normal user session is enough; they don’t have to be admin.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

1.8

3.6

[email protected]

OS Trackers for CVE-2025-21656

vendor	priority	summary	link
`debian`	not yet assigned	CVE-2025-21656 not yet assigned priority: Debian including 1 source packages (linux), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 3, open 2.	https://security-tracker.debian.org/tracker/CVE-2025-21656
`redhat`	—	—	https://access.redhat.com/security/cve/CVE-2025-21656
`suse`	low	CVE-2025-21656 severity low: SUSE including 417 source package names (2.1.3-4.43:kernel-default-base-6.4.0-24.1.21.4, 2.1.3-6.5:kernel-default-6.4.0-25.1, …), 710 product×package rows across 124 product lines (Container suse/sl-micro/6.0/base-os-container, Container suse/sl-micro/6.0/kvm-os-container, … (124 product lines)): Fixed 362, Known Affected 231, Known Not Affected 117.	https://www.suse.com/security/cve/CVE-2025-21656/
`ubuntu`	medium	CVE-2025-21656 medium priority: Ubuntu including 158 source packages (linux, linux-allwinner-5.19, …), 1551 status rows across 10 suites (bionic, focal, jammy, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 1145, ignored 147, released 136, not-affected 90, needed 33.	https://ubuntu.com/security/CVE-2025-21656

Affected software / configurations for CVE-2025-21656

Vendor	Product	Version	Raw CPE
linux	linux_kernel	>= 5.6, < 6.6.72	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.7, < 6.12.10	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	6.13	cpe:2.3:o:linux:linux_kernel:6.13:rc1::::::
linux	linux_kernel	6.13	cpe:2.3:o:linux:linux_kernel:6.13:rc2::::::
linux	linux_kernel	6.13	cpe:2.3:o:linux:linux_kernel:6.13:rc3::::::
linux	linux_kernel	6.13	cpe:2.3:o:linux:linux_kernel:6.13:rc4::::::
linux	linux_kernel	6.13	cpe:2.3:o:linux:linux_kernel:6.13:rc5::::::
linux	linux_kernel	6.13	cpe:2.3:o:linux:linux_kernel:6.13:rc6::::::

References for CVE-2025-21656

URL	Tags
https://git.kernel.org/stable/c/42268d885e44af875a6474f7bba519cc6cea6a9d	Patch
https://git.kernel.org/stable/c/53e25b10a28edaf8c2a1d3916fd8929501a50dfc	Patch
https://git.kernel.org/stable/c/82163d63ae7a4c36142cd252388737205bb7e4b9	Patch

URL

CVE-2025-21656 | hwmon: (drivetemp) Fix driver producing garbage data when SCSI errors occur

Exploit prediction scoring system (EPSS) score for CVE-2025-21656

Common vulnerability scoring system (CVSS) metrics for CVE-2025-21656

Weakness enumeration for CVE-2025-21656

OS Trackers for CVE-2025-21656

Affected software / configurations for CVE-2025-21656

References for CVE-2025-21656