CVE-2026-7387
High
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 Mattermost fails to require role-management authorization when setting the scheme_admin flag on group syncable link and patch endpoints, which allows a user with group-link permissions to escalate themselves and group members to team or channel admin via crafted API requests.. Mattermost Advisory ID: MMSA-2026-00665
SeverityHigh
CVSS8.8
Exploit probability24. percentile0.3%
Product
Mattermost Server
PublishedJun 12, 2026
First seenJun 12, 2026
Weakness typeCWE-863Incorrect authorization
How to fix
Update
- mattermost mattermost_server10.11.17, 11.5.5, 11.6.2 or later
- github.com/mattermost/mattermost-server11.6.1, 11.5.5, 10.11.17, 10.11.17+incompatible, 11.5.5+incompatible, 11.6.1+incompatible or later
- github.com/mattermost/mattermost/server/v88.0.0-20260506065351-202d125afa87 or later
Vendor advisories
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| mattermost mattermost_server | 10.11.0 ≤ v < 10.11.17, 11.5.0 ≤ v < 11.5.5, 11.6.0 ≤ v < 11.6.2 | 10.11.17, 11.5.5, 11.6.2 |
| github.com/mattermost/mattermost-serverGo | 11.6.0 ≤ v < 11.6.1, 11.5.0 ≤ v < 11.5.5, 10.11.0 ≤ v < 10.11.17, 10.11.0+incompatible ≤ v < 10.11.17+incompatible, 11.5.0+incompatible ≤ v < 11.5.5+incompatible, 11.6.0+incompatible ≤ v < 11.6.1+incompatible | 11.6.1, 11.5.5, 10.11.17, 10.11.17+incompatible, 11.5.5+incompatible, 11.6.1+incompatible |
| github.com/mattermost/mattermost/server/v8Go | 8.0.0-20250731163400-5b955468ea1e ≤ v < 8.0.0-20260506065351-202d125afa87 | 8.0.0-20260506065351-202d125afa87 |
| github.com/mattermost/mattermost-server/v5Go | No range specified | — |
| github.com/mattermost/mattermost-server/v6Go | No range specified | — |
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