CVE-2025-38217: linux kernel — Fix

Description

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.

Is your site exposed to CVE-2025-38217?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

4.7

MEDIUM

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

Weakness Type (CWE)

CWE-367 CWE-367

Affected Products

Vendor	Product	Versions
linux	linux_kernel	6.3 — 6.6.95
linux	linux_kernel	6.7 — 6.12.35
linux	linux_kernel	6.13 — 6.15.4
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/14c9ede9ca4cd078ad76a6ab9617b81074eb58bf https://git.kernel.org/stable/c/4d646f627d3b7ed1cacca66e598af8bcd632d465 https://git.kernel.org/stable/c/83e2ba8971ccd8fc08319fc7593288f070d80a76 https://git.kernel.org/stable/c/d95d87841d2a575bed3691884e8fedef57d7710d

Frequently Asked Questions

What is CVE-2025-38217? +

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 has a CVSS v3.1 base score of 4.7 (MEDIUM).

How severe is CVE-2025-38217? +

CVE-2025-38217 has a CVSS v3.1 score of 4.7 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-38217? +

CVE-2025-38217 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-38217? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-5958

When sed is invoked with both -i (in-place edit) and --follow-symlinks, the function open_next_file() performs two separate, non-atomic filesystem operations …

CVE-2026-42336

MaxKB is an open-source AI assistant for enterprise. MaxKB 2.8.0 and prior are vulnerable to a server-side request forgery (SSRF) …

CVE-2025-26620

Duende.AccessTokenManagement is a set of .NET libraries that manage OAuth and OpenId Connect access tokens. Duende.AccessTokenManagement contains a race condition …

CVE-2024-53694

A time-of-check time-of-use (TOCTOU) race condition vulnerability has been reported to affect several product versions. If exploited, the vulnerability could …

CVE-2025-32784

conda-forge-webservices is the web app deployed to run conda-forge admin commands and linting. In versions prior to 2025.4.10, a race …

CVE-2025-34027

The Versa Concerto SD-WAN orchestration platform is vulnerable to an authentication bypass in the Traefik reverse proxy configuration, allowing at …

CVE-2025-38217