CVE-2026-26233

Mattermost versions 11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, 10.11.x <= 10.11.11 fail to rate limit login requests which allows unauthenticated remote attackers to cause denial of service (server crash and restart) via HTTP/2 single packet attack with 100+ parallel login requests.. Mattermost Advisory ID: MMSA-2025-00566

CVSS v3 4.3 MEDIUM

4.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact LOW

Scope UNCHANGED

References

Link	Resource
https://mattermost.com/security-updates	Vendor Advisory

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:mattermost:mattermost_server::::::::
	cpe:2.3:a:mattermost:mattermost_server::::::::
	cpe:2.3:a:mattermost:mattermost_server::::::::
	cpe:2.3:a:mattermost:mattermost_server::::::::

History

26 Mar 2026, 18:52

Type	Values Removed	Values Added
References	~~() https://mattermost.com/security-updates -~~	() https://mattermost.com/security-updates - Vendor Advisory
Summary		(es) Las versiones de Mattermost 11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, 10.11.x <= 10.11.11 no aplican límite de tasa a las solicitudes de inicio de sesión, lo que permite a atacantes remotos no autenticados causar denegación de servicio (caída y reinicio del servidor) mediante un ataque de paquete único HTTP/2 con más de 100 solicitudes de inicio de sesión paralelas. ID de Aviso de Mattermost: MMSA-2025-00566
CPE		cpe:2.3:a:mattermost:mattermost_server::::::::
First Time		Mattermost Mattermost mattermost Server

25 Mar 2026, 17:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-03-25 17:16

Updated : 2026-03-26 18:52

NVD link : CVE-2026-26233

Mitre link : CVE-2026-26233

CVE.ORG link : CVE-2026-26233

JSON object : View

Products Affected

mattermost

mattermost_server

CWE

CWE-400

Uncontrolled Resource Consumption

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