Vulnerability · Published Mar 12, 2026 · Assigned by mitre

CVE-2026-25818

Critical 9.1

In plain English

A critical-severity security flaw in the affected software. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 4% of all known vulnerabilities).

Severity (CVSS 3.1)9.1Critical

Exploit odds (30 days)0.1%top 95.9% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

Vendor	Product	Versions
n/a	n/a	n/a

Weakness: CWE-315 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

References

https://www.hms-networks.com/p/flexy20500-00ma-ewon-flexy-205
https://hmsnetworks.blob.core.windows.net/nlw/docs/default-source/products/cybersecurity/security-advisory/hms-security-advisory-2026-03-09-001---ewon-several-flexy-and-cosy--vulnerabilities.pdf?sfvrsn=f7c027b8_13