CVE-2025-56234

Severity CVSS v4.0:

Pending analysis

Type:

CWE-400 Uncontrolled Resource Consumption ('Resource Exhaustion')

Publication date:

29/09/2025

Last modified:

28/10/2025

Description

AT_NA2000 from Nanda Automation Technology vendor has a denial-of-service vulnerability. For the processing of TCP RST packets, PLC AT_NA2000 has a wide acceptable range of sequence numbers. It does not require the sequence number to exactly match the next expected sequence value, just to be within the current receive window, which violates RFC5961. This flaw allows attackers to send multiple random TCP RST packets to hit the acceptable range of sequence numbers, thereby interrupting normal connections and causing a denial-of-service attack.

Impact

Vector 3.x

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS v3.1 Severity and Metrics:

Base Score: 7.50 HIGH
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): None
Integrity (I): None
Availability (A): High

Base Score 3.x

7.50

Severity 3.x

HIGH

References to Advisories, Solutions, and Tools

https://github.com/zq-star/TCP-Vuln-Report/blob/master/PLC/AT-NA2000/tcp-rst/at-na2000-tcp-rst.md