CVE-2026-25783

Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to properly validate User-Agent header tokens which allows an authenticated attacker to cause a request panic via a specially crafted User-Agent header. Mattermost Advisory ID: MMSA-2026-00586

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::::::::

History

18 Mar 2026, 18:11

Type	Values Removed	Values Added
First Time		Mattermost Mattermost mattermost Server
References	~~() https://mattermost.com/security-updates -~~	() https://mattermost.com/security-updates - Vendor Advisory
CPE		cpe:2.3:a:mattermost:mattermost_server::::::::
Summary		(es) Las versiones de Mattermost 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 no validan correctamente los tokens del encabezado User-Agent, lo que permite a un atacante autenticado causar un pánico de solicitud mediante un encabezado User-Agent especialmente diseñado. ID de Aviso de Mattermost: MMSA-2026-00586

16 Mar 2026, 14:18

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-03-16 14:18

Updated : 2026-03-18 18:11

NVD link : CVE-2026-25783

Mitre link : CVE-2026-25783

CVE.ORG link : CVE-2026-25783

JSON object : View

Products Affected

mattermost

mattermost_server

CWE

CWE-1287

Improper Validation of Specified Type of Input

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