CVE-2026-4274

Published Mar 26, 2026

Last updated a day ago

Overview

Description
Mattermost versions 11.2.x <= 11.2.2, 10.11.x <= 10.11.10, 11.4.x <= 11.4.0, 11.3.x <= 11.3.1 fail to restrict team-level access when processing membership sync from a remote cluster, which allows a malicious remote cluster to grant a user access to an entire private team instead of only the shared channel via sending crafted membership sync messages that trigger team membership assignment. Mattermost Advisory ID: MMSA-2026-00574
Source
responsibledisclosure@mattermost.com
NVD status
Analyzed
Products
mattermost_server

Risk scores

CVSS 3.1

Type
Secondary
Base score
5.4
Impact score
2.5
Exploitability score
2.8
Vector string
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
Severity
MEDIUM

Weaknesses

responsibledisclosure@mattermost.com
CWE-863

Social media

Hype score
Not currently trending

Configurations

References

Sources include official advisories and independent security research.