Siemens SIMATIC S7-1500 TM MFP Improper Input Validation (CVE-2026-46022)

high Tenable OT Security Plugin ID 506474

Synopsis

The remote OT asset is affected by a vulnerability.

Description

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

misc: ibmasm: fix OOB MMIO read in ibmasm_handle_mouse_interrupt()

ibmasm_handle_mouse_interrupt() performs an out-of-bounds MMIO read when the queue reader or writer index from hardware exceeds REMOTE_QUEUE_SIZE (60).

A compromised service processor can trigger this by writing an out-of-range value to the reader or writer MMIO register before asserting an interrupt. Since writer is re-read from hardware on every loop iteration, it can also be set to an out-of-range value after the loop has already started.

The root cause is that get_queue_reader() and get_queue_writer() return raw readl() values that are passed directly into get_queue_entry(), which computes:

queue_begin + reader * sizeof(struct remote_input)

with no bounds check. This unchecked MMIO address is then passed to memcpy_fromio(), reading 8 bytes from unintended device registers.
For sufficiently large values the address falls outside the PCI BAR mapping entirely, triggering a machine check exception.

Fix by checking both indices against REMOTE_QUEUE_SIZE at the top of the loop body, before any call to get_queue_entry(). On an out-of-range value, reset the reader register to 0 via set_queue_reader() before breaking, so that normal queue operation can resume if the corrupted hardware state is transient.

This plugin only works with Tenable.ot.
Please visit https://www.tenable.com/products/tenable-ot for more information.

Solution

Refer to the vendor advisory.

Plugin Details

Severity: High

ID: 506474

File Name: tenable_ot_siemens_CVE-2026-46022.nasl

Version: 1.1

Type: Remote

Family: Tenable.ot

Published: 10/20/2026

Updated: 10/20/2026

Supported Sensors: Tenable OT Security

Risk Information

VPR

Risk Factor: Medium

Score: 4.3

Percentile: 53.44

CVSS v3

Risk Factor: High

Base Score: 7.1

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Vulnerability Information

CPE: cpe:/o:siemens:simatic_s7-1500_tm_mfp

Required KB Items: Tenable.ot/Siemens

Exploit Ease: No known exploits are available

Patch Publication Date: 10/13/2026

Vulnerability Publication Date: 10/13/2026

Reference Information

CVE: CVE-2026-46022

CWE: 20

Detections

Analytics