Siemens SIMATIC, SCALANCE and RUGGEDCOM Devices NULL Pointer Dereference (CVE-2024-50039)

medium Tenable OT Security Plugin ID 503648

Synopsis

The remote OT asset is affected by a vulnerability.

Description

In the Linux kernel, the following vulnerability has been resolved:
net/sched: accept TCA_STAB only for root qdisc Most qdiscs maintain their backlog using qdisc_pkt_len(skb) on the assumption it is invariant between the enqueue() and dequeue() handlers.
Unfortunately syzbot can crash a host rather easily using a TBF + SFQ combination, with an STAB on SFQ [1] We can't support TCA_STAB on arbitrary level, this would require to maintain per-qdisc storage.

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

Solution

The following text was originally created by the Cybersecurity and Infrastructure Security Agency (CISA). The original can be found at CISA.gov.

Siemens has identified the following specific workarounds and mitigations users can apply to reduce risk:

- All affected products: Update to V3.2 or later version

As a general security measure, Siemens recommends protecting network access to devices with appropriate mechanisms. To operate the devices in a protected IT environment, Siemens recommends configuring the environment according to Siemens' operational guidelines for industrial security and following recommendations in the product manuals.

Additional information on industrial security by Siemens can be found on the Siemens industrial security webpage

For more information see the associated Siemens security advisory SSA-355557 in HTML and CSAF.

Plugin Details

Severity: Medium

ID: 503648

File Name: tenable_ot_siemens_CVE-2024-50039.nasl

Version: 1.3

Type: remote

Family: Tenable.ot

Published: 10/27/2025

Updated: 2/12/2026

Supported Sensors: Tenable OT Security

Risk Information

VPR

Risk Factor: Medium

Score: 4.4

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:scalance_xrh-300_series_firmware, cpe:/o:siemens:scalance_xc-300_series_firmware, cpe:/o:siemens:scalance_xc-400_series_firmware, cpe:/o:siemens:scalance_xch-300_series_firmware, cpe:/o:siemens:scalance_xrm-300_series_firmware, cpe:/o:siemens:scalance_xcm-300_series_firmware, cpe:/o:siemens:scalance_xr-500_series_firmware, cpe:/o:siemens:ruggedcom_rst2428p_firmware:3.2, cpe:/o:siemens:scalance_xr-500wg_series_firmware, cpe:/o:siemens:simatic_s7-1500_tm_mfp, cpe:/o:siemens:scalance_xr-300_series_firmware

Required KB Items: Tenable.ot/Siemens

Exploit Ease: No known exploits are available

Patch Publication Date: 4/9/2024

Vulnerability Publication Date: 4/9/2024

Reference Information

CVE: CVE-2024-50039

CWE: 476

ICSA: 25-226-07

Detections

Analytics