Siemens SIMATIC S7-1500 TM MFP Use After Free (CVE-2025-21703)

high Tenable OT Security Plugin ID 506279

Synopsis

The remote OT asset is affected by a vulnerability.

Description

netem: Update sch q.qlen before qdisc_tree_reduce_backlog() qdisc_tree_reduce_backlog() notifies parent qdisc only if child qdisc becomes empty, therefore we need to reduce the backlog of the child qdisc before calling it. Otherwise it would miss the opportunity to call cops qlen_notify(), in the case of DRR, it resulted in UAF since DRR uses qlen_notify() to maintain its active list.

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: 506279

File Name: tenable_ot_siemens_CVE-2025-21703.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: 57.12

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: 3/11/2025

Vulnerability Publication Date: 3/11/2025

Reference Information

CVE: CVE-2025-21703

CWE: 416

Detections

Analytics