CVE-2026-3433

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

State: Published
Severity: 4.3 Medium
Published: Jun 12, 2026
Updated: Jun 12, 2026
Reserved: Mar 2, 2026

Description

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

Scores

CVSS	Score	Vector	Source
3.1	4.3 Medium	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N	Mattermost

Weaknesses

CWE-200 Exposure of Sensitive Information to an Unauthorized Actor

Affected Products

Product	Versions
MattermostMattermost	11.6.0 through 11.6.1Affected 11.5.0 through 11.5.4Affected 10.11.0 through 10.11.15Affected 10.11.0 through 10.11.16Affected 11.7.0Not affected 11.6.2Not affected 11.5.5Not affected 10.11.16Not affected 10.11.17Not affected

References

MMSA-2026-00616vendor-advisory

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