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CVE-2026-18256 Details

Description

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 properly restrict private teams from public team search results, which allows an authenticated user without permission to list private teams to disclose the ID, name, and display name of private teams via a modified team search request. Mattermost Advisory ID: MMSA-2026-00748

Metrics

CVSS 3.x Severity and Vector Strings:

CNA: [email protected]CVSS-B:4.3 MEDIUMVector:CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

References to Advisories, Solutions, and Tools

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URL	Source(s)	Tag(s)
https://mattermost.com/security-updates	[email protected]	Vendor Advisory

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-863	Incorrect Authorization	[email protected]

Affected Products

Product	Versions
mattermost mattermost server	>= 11.7.0, < 11.7.10 >= 11.8.0, < 11.8.6 >= 11.9.0, < 11.9.2 11.10.0
CPE cpe:2.3:a:mattermost:mattermost_server:::::::: cpe:2.3:a:mattermost:mattermost_server:11.10.0:::::::* Remediation No remediation found in references.

Change History

3 change records found show changes

Date	Action	Recorded By
Oct 29, 2026	Initial Analysis	[email protected]
Oct 16, 2026	CVE Modified	CISA-ADP
Oct 16, 2026	New CVE Received	[email protected]