Detections
Analytics

Siemens SIMATIC S7 PLC Web Server Improper Neutralization of Input During Web Page Generation (CVE-2026-25789)

high Tenable OT Security Plugin ID 505540

Synopsis

The remote OT asset is affected by a vulnerability.

Description

Affected devices do not properly validate and sanitize filenames on the Firmware Update page. This could allow a remote attacker to social engineer the user into selecting a modified firmware file.
This would result in malicious JavaScript execution in the context of the authenticated user's session without requiring the file to be uploaded, potentially leading to session hijacking.

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.

See Also

https://cert-portal.siemens.com/productcert/html/ssa-688146.html

https://www.cisa.gov/news-events/ics-advisories/icsa-26-134-15

Plugin Details

Severity: High

ID: 505540

File Name: tenable_ot_siemens_CVE-2026-25789.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: 4.9

Percentile: 57.88

CVSS v2

Risk Factor: High

Base Score: 7.1

Temporal Score: 5.3

Vector: CVSS2#AV:N/AC:H/Au:S/C:C/I:C/A:C

CVSS Score Source: CVE-2026-25789

CVSS v3

Risk Factor: High

Base Score: 7.1

Temporal Score: 6.2

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

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

CVSS v4

Risk Factor: High

Base Score: 7.2

Threat Score: 4.1

Threat Vector: CVSS:4.0/E:U

Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:A/VC:L/VI:H/VA:H/SC:L/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-2026-25789

CWE: 79

ICSA: 26-134-15