Siemens SIMATIC S7-1500 CPU 1518 MFP Improper Input Validation (CVE-2025-38736)

medium Tenable OT Security Plugin ID 505868

Synopsis

The remote OT asset is affected by a vulnerability.

Description

In the Linux kernel, the following vulnerability has been resolved:
net: usb: asix_devices: Fix PHY address mask in MDIO bus initialization Syzbot reported shift-out-of-bounds exception on MDIO bus initialization. The PHY address should be masked to 5 bits (0-31). Without this mask, invalid PHY addresses could be used, potentially causing issues with MDIO bus operations. Fix this by masking the PHY address with 0x1f (31 decimal) to ensure it stays within the valid range.

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: Medium

ID: 505868

File Name: tenable_ot_siemens_CVE-2025-38736.nasl

Version: 1.1

Type: Remote

Family: Tenable.ot

Published: 7/27/2026

Updated: 7/27/2026

Supported Sensors: Tenable OT Security

Risk Information

VPR

Risk Factor: Medium

Score: 4.3

Percentile: 53.35

CVSS v3

Risk Factor: Medium

Base Score: 5.5

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

Vulnerability Information

CPE: cpe:/o:siemens:simatic_s7-1500_cpu_firmware:3.1.6, cpe:/o:siemens:siplus_s7-1500_cpu_firmware

Required KB Items: Tenable.ot/Siemens

Exploit Ease: No known exploits are available

Patch Publication Date: 5/12/2026

Vulnerability Publication Date: 9/5/2025

Reference Information

CVE: CVE-2025-38736

CWE: 20

Detections

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