CVE-2026-25819
Published: 13 March 2026
Summary
CVE-2026-25819 is a high-severity Uncontrolled Resource Consumption (CWE-400) vulnerability in Windows (inferred from references). Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 41.1% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
Threat & Defense at a Glance
Threat & Defense Details
Likely Mitigating ControlsAI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Limiting concurrent sessions directly prevents uncontrolled resource consumption by capping the number of active sessions per user or account.
Analysis identifies uncontrolled resource consumption indicative of denial-of-service or abuse attempts.
Contingency plan testing includes resource exhaustion scenarios to verify recovery, making it harder for attackers to sustain exploits that cause uncontrolled consumption.
Updated contingency plans include current procedures to detect, contain, and recover from resource exhaustion, limiting an attacker's ability to sustain impact from uncontrolled consumption.
Alternate site allows resumption of operations if resource exhaustion at the primary site is exploited to cause unavailability.
Alternate telecommunications services enable resumption of essential functions when primary services become unavailable due to uncontrolled resource consumption.
The team can analyze and respond to resource exhaustion incidents, reducing the impact of attacks that exploit uncontrolled consumption weaknesses.
Timely maintenance support and spare parts enable rapid recovery from failures induced by uncontrolled resource consumption, shortening the impact window of denial-of-service attacks.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
CVE enables unauthenticated exploitation of public-facing HTTP GUI (T1190) to trigger resource exhaustion leading to device reboot/crash (T1499.004).
NVD 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 allows unauthenticated attackers to cause a Denial of Service by using a specially crafted HTTP request that leads to…
more
a reboot of the device, provided they have access to the device's GUI.
Deeper analysisAI
CVE-2026-25819 is a denial-of-service vulnerability in HMS Networks Ewon Flexy and Cosy+ devices. It affects Ewon Flexy with firmware versions before 15.0s4, Cosy+ with firmware 22.xx before 22.1s6, and Cosy+ with firmware 23.xx before 23.0s3. The flaw enables unauthenticated attackers to trigger a device reboot using a specially crafted HTTP request, provided they can access the device's GUI. It carries a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) and maps to CWE-400 (Uncontrolled Resource Consumption).
Any unauthenticated attacker with network access to the affected device's GUI can exploit this vulnerability. By sending the crafted HTTP request, they cause an immediate reboot, disrupting device availability and potentially impacting operational technology environments where these industrial gateways are deployed.
The HMS Networks security advisory (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) addresses this and related vulnerabilities, recommending firmware updates to version 15.0s4 or later for Ewon Flexy, 22.1s6 or later for Cosy+ 22.xx, and 23.0s3 or later for Cosy+ 23.xx as the primary mitigation. Product details are available at https://www.hms-networks.com/p/flexy20500-00ma-ewon-flexy-205.
Details
- CWE(s)