CVE-2026-6342 MEDIUM

CVE-2026-6342: Group prefix matching bypass for subscriptions

Vendor Mattermost
Product Mattermost
Weakness CWE-863 · Incorrect authorization
Published May 18, 2026
Last update May 18, 2026
View on NVD All CVEs

CVSS base score

4.3/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction None
Confidentiality None
Integrity Low

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

What the vulnerability does

01Description

Mattermost Plugins versions <=11.5 11.1.5 10.13.11 11.3.4.0 fail to appropriately check for valid namespaces which allows plugin users to create subscriptions to groups that were not whitelisted via creating groups that share the same prefix as a whitelisted group. Mattermost Advisory ID: MMSA-2026-00601

Key dates

02Disclosure timeline

May 18, 2026 CVE published
May 18, 2026 Record updated