Siemens SIMATIC S7-1500 CPU 1518 MFP Improper Input Validation (CVE-2025-39826)

medium Tenable OT Security Plugin ID 505613

Synopsis

The remote OT asset is affected by a vulnerability.

Description

In the Linux kernel, the following vulnerability has been resolved:
net: rose: convert 'use' field to refcount_t The 'use' field in struct rose_neigh is used as a reference counter but lacks atomicity.
This can lead to race conditions where a rose_neigh structure is freed while still being referenced by other code paths. For example, when rose_neigh->use becomes zero during an ioctl operation via rose_rt_ioctl(), the structure may be removed while its timer is still active, potentially causing use-after-free issues. This patch changes the type of 'use' from unsigned short to refcount_t and updates all code paths to use rose_neigh_hold() and rose_neigh_put() which operate reference counts atomically.

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: 505613

File Name: tenable_ot_siemens_CVE-2025-39826.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: 4.9

Percentile: 57.16

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: 9/16/2025

Reference Information

CVE: CVE-2025-39826

CWE: 20

Detections

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