CVE-2025-39816: linux kernel — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: io_uring/kbuf: always use READ_ONCE() to read ring provided buffer lengths Since the buffers are mapped from userspace, it is prudent to use READ_ONCE() to read the value into a local variable, and use that for any other actions taken. Having a stable read of the buffer length avoids worrying about it changing after checking, or being read multiple times. Similarly, the buffer may well change in between it being picked and being committed. Ensure the looping for incremental ring buffer commit stops if it hits a zero sized buffer, as no further progress can be made at that point.

Is your site exposed to CVE-2025-39816?

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

CVSS v3.1 Score

5.5

MEDIUM

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

Affected Products

Vendor	Product	Versions
linux	linux_kernel	6.12 — 6.12.49
linux	linux_kernel	6.13 — 6.16.5
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/390a61d284e1ced088d43928dfcf6f86fffdd780 https://git.kernel.org/stable/c/695673eb5711ee5eb1769481cf1503714716a7d1 https://git.kernel.org/stable/c/98b6fa62c84f2e129161e976a5b9b3cb4ccd117b

Other References

https://git.kernel.org/stable/c/91f262ea2a76a02d9e37dba6637cfe6feebb20a8

Frequently Asked Questions

What is CVE-2025-39816? +

In the Linux kernel, the following vulnerability has been resolved: io_uring/kbuf: always use READ_ONCE() to read ring provided buffer lengths Since the buffers are mapped from userspace, it is prudent to use READ_ONCE() to read the value into a local variable, and use that for any other actions taken. Having a stable read of the buffer length avoids worrying about it changing after checking, or being read multiple times. Similarly, the buffer may well change in between it being picked and being committed. Ensure the looping for incremental ring buffer commit stops if it hits a zero sized buffer, as no further progress can be made at that point. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-39816? +

CVE-2025-39816 has a CVSS v3.1 score of 5.5 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-2025-39816? +

CVE-2025-39816 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-2025-39816? +

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-2025-9588 10.0

Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') vulnerability in Iron Mountain Archiving Services Inc. …

CVE-2025-57870 10.0

A SQL Injection vulnerability exists in Esri ArcGIS Server versions 11.3, 11.4 and 11.5 on Windows, Linux and Kubernetes. This …

CVE-2026-48286 10.0

Adobe Campaign Classic (ACC) versions 7.4.3 build 9396 and earlier are affected by an Incorrect Authorization vulnerability that could result …

CVE-2026-13782 10.0

Use after free in Browser in Google Chrome prior to 150.0.7871.47 allowed a remote attacker who had compromised the renderer …

CVE-2026-48303 10.0

Adobe Campaign Classic (ACC) versions 7.4.3 build 9394 and earlier are affected by an Incorrect Authorization vulnerability that could result …

CVE-2025-34028 10.0

The Commvault Command Center Innovation Release allows an unauthenticated actor to upload ZIP files that represent install packages that, when …

CVE-2025-39816