Siemens SIMATIC S7-1500 Out-of-bounds Write (CVE-2020-24659)

high Tenable OT Security Plugin ID 504308

Synopsis

The remote OT asset is affected by a vulnerability.

Description

An issue was discovered in GnuTLS before 3.6.15. A server can trigger a NULL pointer dereference in a TLS 1.3 client if a no_renegotiation alert is sent with unexpected timing, and then an invalid second handshake occurs. The crash happens in the application's error handling path, where the gnutls_deinit function is called after detecting a handshake failure.

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: 504308

Version: 1.1

Type: remote

Family: Tenable.ot

Published: 11/13/2025

Updated: 11/13/2025

Supported Sensors: Tenable OT Security

Risk Information

VPR

Risk Factor: Medium

Score: 4.4

CVSS v3

Risk Factor: High

Base Score: 7.5

Temporal Score: 6.7

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

Temporal Vector: CVSS:3.0/E:P/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:siemens:simatic_s7-1500_cpu_firmware:3.1.5, cpe:/o:siemens:siplus_s7-1500_cpu_firmware:3.1.5

Required KB Items: Tenable.ot/Siemens

Exploit Ease: No known exploits are available

Patch Publication Date: 12/12/2023

Vulnerability Publication Date: 12/12/2023

Reference Information

CVE: CVE-2020-24659

CWE: 787

Detections

Analytics