CVE-2026-6333

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13 fail to validate the Host header when constructing response URLs for custom slash commands which allows an authenticated attacker to redirect slash command responses to an attacker-controlled server via a spoofed Host header.. Mattermost Advisory ID: MMSA-2026-00582

CVSS v3 3.5 LOW

3.5^/10

CVSS v3 : LOW

Vector :

Exploitability : 1.8 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required LOW

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact LOW

Availability Impact NONE

Scope CHANGED

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::::::::

History

19 May 2026, 17:51

Type	Values Removed	Values Added
First Time		Mattermost mattermost Server Mattermost
References	~~() https://mattermost.com/security-updates -~~	() https://mattermost.com/security-updates - Vendor Advisory
CPE		cpe:2.3:a:mattermost:mattermost_server::::::::

18 May 2026, 09:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-05-18 09:16

Updated : 2026-05-19 17:51

NVD link : CVE-2026-6333

Mitre link : CVE-2026-6333

CVE.ORG link : CVE-2026-6333

JSON object : View

Products Affected

mattermost

mattermost_server

CWE

CWE-918

Server-Side Request Forgery (SSRF)

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