CVE-2026-18560

Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to validate user’s permissions before other validations which allows non-content reviewers to infer a post’s flagged status via direct API call.. Mattermost Advisory ID: MMSA-2026-00754

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 LOW

Integrity Impact NONE

Availability Impact NONE

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:11.10.0:::::::*

History

29 Oct 2026, 18:08

Type	Values Removed	Values Added
CPE		cpe:2.3:a:mattermost:mattermost_server:11.10.0:::::::* cpe:2.3:a:mattermost:mattermost_server::::::::
First Time		Mattermost mattermost Server Mattermost
References	~~() https://mattermost.com/security-updates -~~	() https://mattermost.com/security-updates - Vendor Advisory

16 Oct 2026, 08:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-16 08:17

Updated : 2026-10-29 18:08

NVD link : CVE-2026-18560

Mitre link : CVE-2026-18560

CVE.ORG link : CVE-2026-18560

JSON object : View

Products Affected

mattermost

mattermost_server

CWE

CWE-203

Observable Discrepancy

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