Linux Linux Kernel Out-Of-Bounds Read Exposed to Unauthenticated Network Attackers

Last refreshed2026-10-15

Status: UPDATED | Advisory ID: CVE-2026-31708

Key Details

CVE	CVE-2026-31708
CVSS Score / Version	8.1 (High) / CVSS v3.1
Updated	2026-10-15
CVSS Vector	`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H`
CVSS Prose	attack vector is network; attack complexity is low; privileges required is none; user interaction is required; scope is unchanged; confidentiality impact is high; integrity impact is none; availability impact is high.
Affected products	Linux Kernel and Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
Classified as	CWE-125 (Out-of-bounds Read)
Exploitation prediction (EPSS)	0.35% probability of exploitation in the next 30 days (27% percentile) -- FIRST.org's EPSS model.

Vendor	Product	Affected Versions	Patch Status
Linux	Linux Kernel
Siemens	SIMATIC S7-1500 TM MFP - GNU/Linux subsystem

Vendor

Product

Affected Versions

Patch Status

Linux

Linux Kernel

Siemens

SIMATIC S7-1500 TM MFP - GNU/Linux subsystem

Subsystems	Controllers & Field I/O, OT Supporting Infrastructure
Sectors	All Sectors

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

smb: client: fix OOB read in smb2_ioctl_query_info QUERY_INFO path

smb2_ioctl_query_info() has two response-copy branches: PASSTHRU_FSCTL

and the default QUERY_INFO path. The QUERY_INFO branch clamps

qi.input_buffer_length to the server-reported OutputBufferLength and then

copies qi.input_buffer_length bytes from qi_rsp->Buffer to userspace, but

it never verifies that the flexible-array payload actually fits within

rsp_iov[1].iov_len.

A malicious server can return OutputBufferLength larger than the actual

QUERY_INFO response, causing copy_to_user() to walk past the response

buffer and expose adjacent kernel heap to userspace.

Guard the QUERY_INFO copy with a bounds check on the actual Buffer

payload. Use struct_size(qi_rsp, Buffer, qi.input_buffer_length)

rather than an open-coded addition so the guard cannot overflow on

32-bit builds. (NVD)

Monitor Linux's and Siemens's web pages for any future patch releases.

Source	Reference
NVD	https://nvd.nist.gov/vuln/detail/CVE-2026-31708
CVE	https://www.cve.org/CVERecord?id=CVE-2026-31708

Source

Reference

NVD

CVE