CyberSecBulletin
CVE-2026-31401NVD status: Modified

Linux: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2026-31401 is a high-severity out-of-bounds write vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions d6efaa50af62fb0790dd1fd4e7e5506b46312510, 73c5b5aea1c443239c8cb4191b4af7a4bd6fd7b1, eb57dae20fdf6f3069cdc07821fa3bb46de381d7 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.14% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to d6efaa50af62fb0790dd1fd4e7e5506b46312510 or 73c5b5aea1c443239c8cb4191b4af7a4bd6fd7b1 or eb57dae20fdf6f3069cdc07821fa3bb46de381d7 or 2b658c1c442ec1cd9eec5ead98d68662c40fe645, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.12.78 or 6.18.20 or 6.19.10, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux8bd0488b5ea58655ad6fdcbe0408ef49b16882b1 up to, but not including, d6efaa50af62fb0790dd1fd4e7e5506b46312510; 8bd0488b5ea58655ad6fdcbe0408ef49b16882b1 up to, but not including, 73c5b5aea1c443239c8cb4191b4af7a4bd6fd7b1; 8bd0488b5ea58655ad6fdcbe0408ef49b16882b1 up to, but not including, eb57dae20fdf6f3069cdc07821fa3bb46de381d7; 8bd0488b5ea58655ad6fdcbe0408ef49b16882b1 up to, but not including, 2b658c1c442ec1cd9eec5ead98d68662c40fe645; 6.11d6efaa50af62fb0790dd1fd4e7e5506b46312510, 73c5b5aea1c443239c8cb4191b4af7a4bd6fd7b1, eb57dae20fdf6f3069cdc07821fa3bb46de381d7, 2b658c1c442ec1cd9eec5ead98d68662c40fe645
LinuxLinux Kernel6.11 up to, but not including, 6.12.78; 6.13 up to, but not including, 6.18.20; 6.19 up to, but not including, 6.19.10; 7.06.12.78, 6.18.20, 6.19.10

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: HID: bpf: prevent buffer overflow in hid_hw_request right now the returned value is considered to be always valid. However, when playing with HID-BPF, the return value can be arbitrary big, because it's the return value of dispatch_hid_bpf_raw_requests(), which calls the struct_ops and we have no guarantees that the value makes sense.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Out-of-bounds Write

The product writes data past the end, or before the beginning, of the intended buffer.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.

More Out-of-bounds Write vulnerabilities (CWE-787)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Out-of-bounds Write vulnerabilities

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