Siemens SIMATIC S7 PLC Web Server Improper Neutralization of Input During Web Page Generation (CVE-2026-25786)

critical Tenable OT Security Plugin ID 505539

Synopsis

The remote OT asset is affected by a vulnerability.

Description

Affected devices do not properly validate and sanitize PLC/station name rendered on the 'communication' parameters page of the web interface. This could allow an authenticated attacker who is authorized to download a TIA project into the product, to inject malicious scripts into the page. If a benign user with appropriate rights accesses the 'communication' parameters page, the malicious code would be executed in the scope of their web session.

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.

Plugin Details

Severity: Critical

ID: 505539

File Name: tenable_ot_siemens_CVE-2026-25786.nasl

Version: 1.4

Type: Remote

Family: Tenable.ot

Published: 7/6/2026

Updated: 7/15/2026

Supported Sensors: Tenable OT Security

Risk Information

VPR

Risk Factor: Medium

Score: 5

Percentile: 94.14

CVSS v2

Risk Factor: High

Base Score: 8.3

Temporal Score: 6.1

Vector: CVSS2#AV:N/AC:L/Au:M/C:C/I:C/A:C

CVSS Score Source: CVE-2026-25786

CVSS v3

Risk Factor: Critical

Base Score: 9.1

Temporal Score: 7.9

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

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

CVSS v4

Risk Factor: Critical

Base Score: 9.3

Threat Score: 7.4

Threat Vector: CVSS:4.0/E:U

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Vulnerability Information

CPE: cpe:/o:siemens:simatic_et200pro_firmware, cpe:/o:siemens:simatic_s7-1500_cpu_firmware, cpe:/o:siemens:simatic_et200sp_firmware, cpe:/o:siemens:siplus_s7-1500_cpu_firmware

Required KB Items: Tenable.ot/Siemens

Exploit Ease: No known exploits are available

Patch Publication Date: 5/12/2026

Vulnerability Publication Date: 5/12/2026

Reference Information

CVE: CVE-2026-25786

CWE: 79

ICSA: 26-134-15

Detections

Analytics