CVE-2026-3433CWE-200

Mattermost fails to scope role_updated websocket events to authorized team and channel members

Medium · published June 12, 2026

CVSS v3.1
4.3
EPSS
0%
Percentile
21.7
In the wild
Unconfirmed
What it is

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

The record
Technical detail
CVSS v3.1
4.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
CVSS v4.0
Not supplied
EPSS
0.00301 · 21.7th percentile
Weakness
CWE-200 · Exposure of Sensitive Information to an Unauthorized Actor
Published
2026-06-12T15:46Z
EPSS history
Timeline
  • 12 JUN 15:46Z
    Mattermost fails to scope role_updated websocket events to authorized team and channel members
    cvelistv5