CVEvulnerability

CVE-2026-28759

4.3 MEDIUM Published 2026-05-18 Modified 2026-10-14 Official page ↗
Status
Analyzed
Published
2026-05-18
Last modified
2026-10-14
Assigner
[email protected]
CVSS 3.1 ([email protected])
4.3 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Weaknesses
CWE-863

Description

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to validate that a remote cluster has access to a channel before processing membership removal requests during shared channel membership sync, which allows a malicious remote cluster to remove any user from any channel, including private channels, via crafted membership sync messages targeting channels the remote cluster is not authorized to access. Mattermost Advisory ID: MMSA-2026-00576

Affected configurations

• mattermost mattermost server (>= 10.11.0 < 10.11.14) • mattermost mattermost server (>= 11.4.0 < 11.4.4) • mattermost mattermost server (>= 11.5.0 < 11.5.2)

Related

Weakness · CWE (1)

  • CWE-863 Incorrect Authorization weakness

References