CVE-2026-31786

Last refreshed2026-10-17

Status: UPDATED | Advisory ID: CVE-2026-31786

Key Details

CVE	CVE-2026-31786
CVSS Score / Version	7.8 (High) / CVSS v3.1
Updated	2026-10-16
CVSS Vector	`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`
CVSS Prose	attack vector is local; attack complexity is low; privileges required is low; user interaction is none; scope is unchanged; confidentiality impact is high; integrity impact is high; availability impact is high.
Affected products	Linux Kernel
Classified as	CWE-787 (Out-of-bounds Write)

Vendor	Product	Affected Versions	Patch Status
Linux	Linux Kernel

Vendor

Product

Affected Versions

Patch Status

Linux

Linux Kernel

Subsystems	OT Supporting Infrastructure
Sectors	All Sectors

In the Linux kernel, the following vulnerability has been resolved:

Buffer overflow in drivers/xen/sys-hypervisor.c

The build id returned by HYPERVISOR_xen_version(XENVER_build_id) is

neither NUL terminated nor a string.

The first causes a buffer overflow as sprintf in buildid_show will

read and copy till it finds a NUL.

00000000 f4 91 51 f4 dd 38 9e 9d 65 47 52 eb 10 71 db 50 |..Q..8..eGR..q.P|

00000010 b9 a8 01 42 6f 2e 32 |...Bo.2|

00000017

So use a memcpy instead of sprintf to have the correct value:

00000000 f4 91 51 f4 dd 00 9e 9d 65 47 52 eb 10 71 db 50 |..Q.....eGR..q.P|

00000010 b9 a8 01 42 |...B|

00000014

(the above have a hack to embed a zero inside and check it's

returned correctly).

This is XSA-485 / CVE-2026-31786 (NVD)

Monitor Linux's web page for any future patch releases.

Source	Reference
NVD	https://nvd.nist.gov/vuln/detail/CVE-2026-31786
CVE	https://www.cve.org/CVERecord?id=CVE-2026-31786

Source

Reference

NVD

CVE