CVE-2026-25818
Received Received - Intake

Weak Entropy in HMS Networks Ewon Flexy Authentication Cookies

Publication date: 2026-03-13

Last updated on: 2026-03-13

Assigner: MITRE

Description
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.

CVSS Scores

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Meta Information

Published
2026-03-13
Last Modified
2026-03-13
Generated
2026-07-06
AI Q&A
2026-03-13
EPSS Evaluated
2026-07-05
NVD
CVE-2026-25818
EUVD
EUVD-2026-11711

Affected Vendors & Products

Showing 5 associated CPEs
Vendor Product Version / Range
hms_networks cosy_plus to 22.1s6 (exc)
hms_networks cosy_plus to 23.0s3 (exc)
hms_networks ewon_flexy to 15.0s4 (exc)
hms_networks cosy to 22.1s6 (exc)
hms_networks cosy to 23.0s3 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-315 The product stores sensitive information in cleartext in a cookie.

Attack-Flow Graph

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Executive Summary

This vulnerability affects HMS Networks Ewon Flexy and Cosy+ devices with certain firmware versions. The issue is that these devices use weak entropy for authentication cookies. Because of this weakness, an attacker who has stolen a session cookie can brute-force an encryption parameter to discover the user's password.

Impact Analysis

The vulnerability can have a severe impact because it allows an attacker to obtain the user password by brute-forcing an encryption parameter after stealing a session cookie. This can lead to unauthorized access with high confidentiality and integrity impact, as indicated by the CVSS score of 9.1.

Compliance Impact

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Detection Guidance

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Mitigation Strategies

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