CVE-2026-3433 MEDIUM

CVE-2026-3433: Mattermost fails to scope role_updated websocket events to authorized team and channel members

Vendor Mattermost
Product Mattermost
Weakness CWE-200 · Info exposure
Published June 12, 2026
Last update June 12, 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 Low
Integrity None

CVSS vector

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

What the vulnerability does

01Description

Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 fail to restrict role_updated websocket event broadcasts to members of the affected team or channel which allows an authenticated attacker with guest-level access to observe permission scheme change notifications for private teams they are not a member of via the websocket connection.. Mattermost Advisory ID: MMSA-2026-00616

Key dates

02Disclosure timeline

June 12, 2026 CVE published
June 12, 2026 Record updated