CVE-2026-26230

Low

Description

Mattermost versions 10.11.x <= 10.11.10 fail to properly validate permission requirements in the team member roles API endpoint which allows team administrators to demote members to guest role. Mattermost Advisory ID: MMSA-2025-00531

SeverityLow

CVSS3.8

Exploit probability—

Product

Mattermost Server

PublishedMar 16, 2026

First seenMar 16, 2026

Weakness typeCWE-863Incorrect authorization

How to fix

Update

mattermost mattermost_server10.11.11 or later

Vendor advisories

mattermost.com/security-updates

Affected products

Product	Affected versions	Fixed in
mattermost mattermost_server	10.11.0 ≤ v < 10.11.11	10.11.11

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