Detections
Analytics

Siemens Interniche IP-Stack Improper Verification of Source of a Communication Channel (CVE-2025-40820)

high Tenable OT Security Plugin ID 505891

Synopsis

The remote OT asset is affected by a vulnerability.

Description

Multiple Industrial products are affected by a vulnerability in the Interniche IP-Stack. The affected products do not properly enforce TCP sequence number validation in specific scenarios but accept values within a broad range. This could allow an unauthenticated remote attacker e.g. to interfere with connection setup, potentially leading to a denial of service. The attack succeeds only if an attacker can inject IP packets with spoofed addresses at precisely timed moments, and it affects only TCP-based services.

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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-915282.html

https://www.cisa.gov/news-events/ics-advisories/icsa-25-352-05

Plugin Details

Severity: High

ID: 505891

File Name: tenable_ot_siemens_CVE-2025-40820.nasl

Version: 1.4

Type: Remote

Family: Tenable.ot

Published: 7/30/2026

Updated: 8/7/2026

Supported Sensors: Tenable OT Security

Risk Information

VPR

Risk Factor: Low

Score: 3

Percentile: 23.36

CVSS v2

Risk Factor: High

Base Score: 7.8

Temporal Score: 5.8

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

CVSS Score Source: CVE-2025-40820

CVSS v3

Risk Factor: High

Base Score: 7.5

Temporal Score: 6.5

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:U/RL:O/RC:C

CVSS v4

Risk Factor: High

Base Score: 8.7

Threat Score: 6.6

Threat Vector: CVSS:4.0/E:U

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

Vulnerability Information

CPE: cpe:/o:siemens:simatic_s7-1200_cpu_firmware:4.4.0, cpe:/o:siemens:siplus_s7-1200_cpu_firmware:4.4.0

Required KB Items: Tenable.ot/Siemens

Exploit Ease: No known exploits are available

Patch Publication Date: 12/9/2025

Vulnerability Publication Date: 12/9/2025

Reference Information

CVE: CVE-2025-40820

CWE: 940