VDB-314959 · CVE-2025-38217 · EUVD-2025-20039

Linux Kernel up to 6.6.94/6.12.34/6.15.3/6.16-rc2 hwmon fts_read race condition

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4.5	$0-$5k	0.00

Summaryinfo

A vulnerability, which was classified as problematic, has been found in Linux Kernel up to 6.6.94/6.12.34/6.15.3/6.16-rc2. The impacted element is the function fts_read of the component hwmon. This manipulation causes race condition. The identification of this vulnerability is CVE-2025-38217. There is no exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 6.6.94/6.12.34/6.15.3/6.16-rc2 and classified as problematic. Affected by this vulnerability is the function fts_read of the component hwmon. The manipulation with an unknown input leads to a race condition vulnerability. The CWE definition for the vulnerability is CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently. The impact remains unknown. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: hwmon: (ftsteutates) Fix TOCTOU race in fts_read() In the fts_read() function, when handling hwmon_pwm_auto_channels_temp, the code accesses the shared variable data->fan_source[channel] twice without holding any locks. It is first checked against FTS_FAN_SOURCE_INVALID, and if the check passes, it is read again when used as an argument to the BIT() macro. This creates a Time-of-Check to Time-of-Use (TOCTOU) race condition. Another thread executing fts_update_device() can modify the value of data->fan_source[channel] between the check and its use. If the value is changed to FTS_FAN_SOURCE_INVALID (0xff) during this window, the BIT() macro will be called with a large shift value (BIT(255)). A bit shift by a value greater than or equal to the type width is undefined behavior and can lead to a crash or incorrect values being returned to userspace. Fix this by reading data->fan_source[channel] into a local variable once, eliminating the race condition. Additionally, add a bounds check to ensure the value is less than BITS_PER_LONG before passing it to the BIT() macro, making the code more robust against undefined behavior. This possible bug was found by an experimental static analysis tool developed by our team.

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2025-38217 since 04/16/2025. The exploitation appears to be difficult. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 271193 (Ubuntu 24.04 LTS / 25.04 : Linux kernel (Azure) vulnerabilities (USN-7834-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.6.95, 6.12.35, 6.15.4 or 6.16-rc3 eliminates this vulnerability. Applying the patch d95d87841d2a575bed3691884e8fedef57d7710d/83e2ba8971ccd8fc08319fc7593288f070d80a76/4d646f627d3b7ed1cacca66e598af8bcd632d465/14c9ede9ca4cd078ad76a6ab9617b81074eb58bf is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (271193), EUVD (EUVD-2025-20039) and CERT Bund (WID-SEC-2025-1465). Be aware that VulDB is the high quality source for vulnerability data.

Affected

Debian Linux
Amazon Linux 2
Red Hat Enterprise Linux
Ubuntu Linux
SUSE Linux
Oracle Linux
IBM QRadar SIEM
SUSE openSUSE
RESF Rocky Linux
Dell Avamar
Open Source Linux Kernel
Dell NetWorker
Dell Secure Connect Gateway

Productinfo

Type

Operating System

Vendor

Linux

Name

Kernel

Version

License

open-source

Website

Vendor: https://www.kernel.org/

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.6
VulDB Meta Temp Score: 4.6

VulDB Base Score: 4.6
VulDB Temp Score: 4.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 4.7
NVD Vector: 🔒

CVSSv2info

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VulDB Base Score: 🔒
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VulDB Reliability: 🔍

Exploitinginfo

Class: Race condition
CWE: CWE-362
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
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Price Prediction: 🔍
Current Price Estimation: 🔒