Linux Linux Kernel Out-Of-Bounds Write Rated 7.8 CVSS

Last refreshed2026-10-15

Status: UPDATED | Advisory ID: CVE-2026-31696

Key Details

CVE	CVE-2026-31696
CVSS Score / Version	7.8 (High) / CVSS v3.1
Updated	2026-10-15
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 and Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
Classified as	CWE-787 (Out-of-bounds Write)
Exploitation prediction (EPSS)	0.18% probability of exploitation in the next 30 days (7% 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:

rxrpc: Fix missing validation of ticket length in non-XDR key preparsing

In rxrpc_preparse(), there are two paths for parsing key payloads: the

XDR path (for large payloads) and the non-XDR path (for payloads <= 28

bytes). While the XDR path (rxrpc_preparse_xdr_rxkad()) correctly

validates the ticket length against AFSTOKEN_RK_TIX_MAX, the non-XDR

path fails to do so.

This allows an unprivileged user to provide a very large ticket length.

When this key is later read via rxrpc_read(), the total

token size (toksize) calculation results in a value that exceeds

AFSTOKEN_LENGTH_MAX, triggering a WARN_ON().

[ 2001.302904] WARNING: CPU: 2 PID: 2108 at net/rxrpc/key.c:778 rxrpc_read+0x109/0x5c0 [rxrpc]

Fix this by adding a check in the non-XDR parsing path of rxrpc_preparse()

to ensure the ticket length does not exceed AFSTOKEN_RK_TIX_MAX,

bringing it into parity with the XDR parsing logic. (NVD)

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

Source	Reference
NVD	https://nvd.nist.gov/vuln/detail/CVE-2026-31696
CVE	https://www.cve.org/CVERecord?id=CVE-2026-31696

Source

Reference

NVD

CVE