CVE-2026-4055
Medium
Description
Mattermost versions 11.5.x <= 11.5.1 fail to validate team-level run_create permission against the target team when creating a playbook run which allows an authenticated team member to create runs in teams where they lack permission via specifying a different team ID in the run creation API request. Mattermost Advisory ID: MMSA-2026-00629
SeverityMedium
CVSS4.3
Exploit probability—
Product
Mattermost Server
PublishedMay 21, 2026
First seenMay 21, 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/server/v88.0.0-20260320113102-f2b3d1c6a945 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/server/v8Go | 8.0.0-20260304132957-9f2616376582 ≤ v < 8.0.0-20260320113102-f2b3d1c6a945 | 8.0.0-20260320113102-f2b3d1c6a945 |
| github.com/mattermost/mattermost-serverGo | No range specified | — |
| github.com/mattermost/mattermost-server/v5Go | No range specified | — |
| github.com/mattermost/mattermost-server/v6Go | No range specified | — |
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