Siemens SIMATIC S7-1500 TM MFP Missing Release of Memory after Effective Lifetime (CVE-2026-43502)

high Tenable OT Security Plugin ID 506460

Synopsis

The remote OT asset is affected by a vulnerability.

Description

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

net/rds: handle zerocopy send cleanup before the message is queued

A zerocopy send can fail after user pages have been pinned but before the message is attached to the sending socket.

The purge path currently infers zerocopy state from rm->m_rs, so an unqueued message can be cleaned up as if it owned normal payload pages.
However, zerocopy ownership is really determined by the presence of op_mmp_znotifier, regardless of whether the message has reached the socket queue.

Capture op_mmp_znotifier up front in rds_message_purge() and use it as the cleanup discriminator. If the message is already associated with a socket, keep the existing completion path. Otherwise, drop the pinned page accounting directly and release the notifier before putting the payload pages.

This keeps early send failure cleanup consistent with the zerocopy lifetime rules without changing the normal queued completion path.

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: 506460

File Name: tenable_ot_siemens_CVE-2026-43502.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: 4.9

Percentile: 58.46

CVSS v3

Risk Factor: High

Base Score: 7.8

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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-2026-43502

CWE: 401

Detections

Analytics