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CVE-2021-31401
An issue was discovered in tcp_rcv() in nptcp.c in HCC embedded InterNiche 4.0.1. The TCP header processing code doesn't sanitize the value of the IP total length field (header length + data length). With a crafted IP packet, an integer overflow occurs whenever the value of the IP data length is calculated by subtracting the length of the header from the total length of the IP packet.
This record: live connection— last retrieved: 7 November 2026 at 02:35.
Vendors
Products
Base-Device PNOZ mxp ETH (PNOZmulti Classic), PNOZ m B1, PNOZ m ES ETH, PNOZ mmc1p ETH, PSSu-Module for decentralised E/A-System, PSSu-Module for PSS 4000 and 1 more
up to version vers:all/*
Published
19 August 2021
Last modified
17 June 2026
Taken directly from NVD, CISA or the vendor — sometimes in English, unchanged from the source.
An issue was discovered in tcp_rcv() in nptcp.c in HCC embedded InterNiche 4.0.1. The TCP header processing code doesn't sanitize the value of the IP total length field (header length + data length). With a crafted IP packet, an integer overflow occurs whenever the value of the IP data length is calculated by subtracting the length of the header from the total length of the IP packet.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
NETWORK
Privileges required
NONE
User interaction
NONE
Confidentiality
None
Integrity
None
Availability
High
Probability of exploitation within 30 days
2.3%
Percentile
83e
Source: FIRST.org, updated on 6 November 2026.
It is adviced to use firewalls or similar network security devices to prevent unauthorized network communication to the products affected.
Our own interpretation and context for the source data above.
IACS Radar assessment
Our own interpretation and context for this vulnerability — not an official source.
IACS Radar priority score
Based on CVSS 7.5, EPSS 2.3%, industrial relevance 40/100.
Combines CVSS, EPSS, KEV status, industrial relevance and exposure relevance — a complement to, not a replacement for, the individual scores below and above.
Conditions for exploitation
Operational impact & energy relevance
Possible loss of visibility of or control over the process upon successful exploitation.
No strong energy-sector-specific signals recognised; general OT/ICS relevance.
Recommended defensive measures
Industrial relevance score
Classification is provisional; manual verification by an OT security analyst is recommended.
Classified by IACS Radar-analysepijplijn (geautomatiseerd) on 7 November 2026.
IEC 62443 mapping
Automatic IACS Radar assessment based on the reported CWE weakness classification; not an official certification statement.