CVE-2025-27256

High

Published: 10 March 2025

Published

10 March 2025

Modified

15 April 2026

KEV Added

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Patch

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CVSS Score 8.3 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H

EPSS Score 0.0001 1.0th percentile

Risk Priority 17 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2025-27256 is a high-severity Missing Authentication for Critical Function (CWE-306) vulnerability in Gevernova (inferred from references). Its CVSS base score is 8.3 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Adversary-in-the-Middle (T1557); ranked at the 1.0th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified are NIST 800-53 AC-17 (Remote Access) and IA-9 (Service Identification and Authentication).

Threat & Defense at a Glance

What attackers do: exploitation maps to Adversary-in-the-Middle (T1557). What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

IA-9 Service Identification and Authentication good match

prevent

Requires unique identification and authentication of system services like the SSH server before establishing communications, directly preventing authentication bypass and MITM attacks.

SC-23 Session Authenticity good match

prevent

Protects the authenticity of communications sessions, ensuring clients verify the SSH server's legitimacy and blocking MITM exploitation.

AC-17 Remote Access good match

prevent

Mandates cryptographic protection for remote access connections like SSH to prevent unauthorized interception and MITM attacks on adjacent networks.

MITRE ATT&CK Enterprise TechniquesAI

T1557 Adversary-in-the-Middle Credential Access

Adversaries may attempt to position themselves between two or more networked devices using an adversary-in-the-middle (AiTM) technique to support follow-on behaviors such as [Network Sniffing](https://attack.

attack.mitre.org →

Why these techniques?

The CVE description explicitly indicates that the missing SSH server authentication enables a man-in-the-middle (MITM) attack on the network, directly mapping to the Adversary-in-the-Middle technique (T1557).

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

NVD Description

Missing Authentication for Critical Function vulnerability in GE Vernova Enervista UR Setup application allows Authentication Bypass due to a missing SSH server authentication. Since the client connection is not authenticated, an attacker may perform a man-in-the-middle attack on the network.

Deeper analysisAI

CVE-2025-27256 is a Missing Authentication for Critical Function vulnerability (CWE-306) in the GE Vernova Enervista UR Setup application. The flaw arises from a missing SSH server authentication mechanism, which allows authentication bypass. As a result, client connections to the application are not authenticated, enabling an attacker to perform a man-in-the-middle (MITM) attack on the network. The vulnerability carries a CVSS v3.1 base score of 8.3 (AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H) and was published on 2025-03-10.

An attacker on an adjacent network (AV:A) can exploit this vulnerability with low complexity (AC:L), no privileges (PR:N), and no user interaction (UI:N). By positioning themselves to intercept unauthenticated SSH connections, the attacker can conduct a MITM attack, achieving low confidentiality impact alongside high integrity (I:H) and availability (A:H) impacts on the targeted system.

Mitigation guidance is provided in advisories from the vendor and third-party researchers, including GE Vernova's security bulletin at https://www.gevernova.com/grid-solutions/app/DownloadFile.aspx?prod=urfamily&type=21&file=76 and Nozomi Networks' vulnerability advisory at https://www.nozominetworks.com/labs/vulnerability-advisories-cve-2025-27256. Security practitioners should review these resources for patching details and recommended workarounds.