Siemens SIMATIC S7-1500 Incorrect Type Conversion or Cast (CVE-2020-10735)

high Tenable OT Security Plugin ID 504143

Synopsis

The remote OT asset is affected by a vulnerability.

Description

A flaw was found in python. In algorithms with quadratic time complexity using non-binary bases, when using int(text), a system could take 50ms to parse an int string with 100,000 digits and 5s for 1,000,000 digits (float, decimal, int.from_bytes(), and int() for binary bases 2, 4, 8, 16, and 32 are not affected). The highest threat from this vulnerability is to system availability.

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: 504143

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:scalance_xcm332_firmware:2.4, cpe:/o:siemens:scalance_xrh334_%2824_v_dc%2c_8xfo%2c_cc%29_firmware:2.4, cpe:/o:siemens:scalance_xrm334_%28230_v_ac%2c_8xfo%29_firmware:2.4, cpe:/o:siemens:scalance_xch328_firmware:2.4, cpe:/o:siemens:scalance_xrm334_%2824_v_dc%2c_12xfo%29_firmware:2.4, cpe:/o:siemens:scalance_xrm334_%2824_v_dc%2c_8xfo%29_firmware:2.4, cpe:/o:siemens:scalance_xrm334_%282x230_v_ac%2c_12xfo%29_firmware:2.4, cpe:/o:siemens:scalance_xrm334_%28230_v_ac%2c_12xfo%29_firmware:2.4, cpe:/o:siemens:siplus_s7-1500_cpu_firmware:3.1.5, cpe:/o:siemens:scalance_xrm334_%282x230_v_ac%2c_8xfo%29_firmware:2.4, cpe:/o:siemens:scalance_xcm328_firmware:2.4, cpe:/o:siemens:scalance_xcm324_firmware:2.4, cpe:/o:siemens:simatic_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-2020-10735

CWE: 704

Detections

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