What is the CVSS score of CVE-2026-25818?

CVE-2026-25818 has a CVSS 3.1 base score of 9.1 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N. EPSS exploitation probability: 0.0%.

How to fix or mitigate CVE-2026-25818?

Within 24 hours: Inventory all HMS Networks Ewon routers in your environment and identify affected firmware versions (Flexy <15.0s4, Cosy+ 22.xx <22.1s6, Cosy+ 23.xx <23.0s3). Within 7 days: Implement network segmentation to isolate affected routers from untrusted networks, disable remote management features if not operationally critical, and monitor session logs for suspicious authentication attempts. Within 30 days: Contact HMS Networks for patch availability confirmation, establish an upgrade schedule, and conduct security testing post-patch deployment.

CVE-2026-25818

EUVD-2026-11711 CRITICAL

Cleartext Storage of Sensitive Information in a Cookie (CWE-315)

2026-03-13 cve@mitre.org

Information Disclosure

9.1

CVSS 3.1 · NVD

View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Obtain stolen session cookie
Exploit

Brute-force weak entropy encryption parameter
Execution

Decrypt user password
Impact

Gain authenticated access to device

Vulnerability Assessment

Weakness	CWE CWE-315 OWASP Top 10:2025 A02:2025 - Security Misconfiguration ASVS 5.0 V14 - Data Protection Cookie data protection
Exploitation Conditions	HMS Networks Ewon Flexy firmware before 15.0s4, Cosy+ firmware 22.xx before 22.1s6, or Cosy+ firmware 23.xx before 23.0s3 with weak entropy authentication cookies. Attacker must obtain a valid session cookie through interception or other means.
Impact	CVSS 9.1. Industrial remote access gateways.
Exploit ScenarioDerived	Decrypt communications.

Act Now Prioritize within 24-48h. Why: CRITICAL severity.

No patch listed yet 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 13, 2026

Weak encryption in HMS Networks Ewon Flexy/Cosy+ firmware.

Earlier versions of this analysis (1)

v1 Mar 13, 2026 - 20:00 CVSS 9.1

Weak crypto in HMS Ewon industrial gateways.

RemediationAI

Update firmware.

Affected VersionsENISA

n/a n/a

Affects your stack

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Technical ContextAI · show details

CWE-315.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 9.1 CRITICAL

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

None

DescriptionCVE.org

HMS Networks Ewon Flexy with firmware before 15.0s4, Cosy+ with firmware 22.xx before 22.1s6, and Cosy+ with firmware 23.xx before 23.0s3 have weak entropy for authentication cookies, allowing an attacker with a stolen session cookie to find the user password by brute-forcing an encryption parameter.

Executive ViewAI

Why It Matters

HMS Networks industrial routers (Flexy and Cosy+ models) contain a critical authentication bypass vulnerability that could allow attackers to compromise user credentials and gain unauthorized access to industrial control systems. Organizations using affected firmware versions face potential operational disruption and unauthorized access to critical infrastructure, though current exploit likelihood remains low.

Business Impact: High

Compensating Controls

Implement strict network segmentation restricting access to affected routers to trusted networks only; disable or restrict remote access/web management interfaces where operationally feasible; deploy network monitoring to detect brute-force attempts against router authentication; enforce VPN requirements for all administrative access; implement firewall rules limiting access to management ports (80, 443); monitor and review session logs for anomalous authentication patterns; consider placing affected devices behind a WAF configured to rate-limit authentication attempts.

Threat Intelligence Overview

EPSS Score

0.0%

Top 97% exploitable

Data Quality

5 sources

Confidence: Medium

EUVD

NVD

CVE.org

EPSS

VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity CRITICAL

CISA KEV No

Public POC No

EPSS 0.0%

Patch available No

Active threat No

Deciding rule

CRITICAL severity

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

Yes

Human Impact

High

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +46

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.