Siemens SIMATIC S7-1500 URL Redirection to Untrusted Site (CVE-2021-28861)

high Tenable OT Security Plugin ID 504105

Synopsis

The remote OT asset is affected by a vulnerability.

Description

Python 3.x through 3.10 has an open redirection vulnerability in lib/http/server.py due to no protection against multiple (/) at the beginning of URI path which may leads to information disclosure. NOTE:
this is disputed by a third party because the http.server.html documentation page states Warning: http.server is not recommended for production. It only implements basic security checks.

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: 504105

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: 5.2

CVSS v3

Risk Factor: High

Base Score: 7.4

Temporal Score: 6.7

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

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-2021-28861

CWE: 601

Detections

Analytics