CVE-2026-25823
Buffer overflow on HMS Ewon Flexy/Cosy+ enables unauthenticated RCE and DoS.
Is CVE-2026-25823 being exploited?
Not confirmed. CVE-2026-25823 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.73% probability of exploitation in the next 30 days.
How severe is CVE-2026-25823?
CVE-2026-25823 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-25823?
Yes. A fix has been recorded for CVE-2026-25823. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-25823 affect?
CVE-2026-25823 affects HMS Networks Ewon Flexy (firmware < 15.0s4), HMS Networks Cosy+ (firmware < 22.1s6), HMS Networks Cosy+ (firmware < 23.0s3). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-25823?
Upgrade to fixed firmware: Flexy 15.0s4+, Cosy+ 22.1s6+/23.0s3+.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
RCE and DoS via stack overflow; attacker can run code on device without auth.
Immediate action required