CVE-2026-20796
Low
Description
Mattermost versions 10.11.x <= 10.11.9 fail to properly validate channel membership at the time of data retrieval which allows a deactivated user to learn team names they should not have access to via a race condition in the /common_teams API endpoint.. Mattermost Advisory ID: MMSA-2025-00549
SeverityLow
CVSS3.1
Exploit probability—
Product
Mattermost Server
PublishedFeb 13, 2026
First seenFeb 13, 2026
Weakness typeCWE-367CWE-367
How to fix
Update
- mattermost mattermost_server10.11.10 or later
- github.com/mattermost/mattermost-server10.11.10, 10.11.10+incompatible or later
Vendor advisories
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| mattermost mattermost_server | 10.11.0 ≤ v < 10.11.10 | 10.11.10 |
| github.com/mattermost/mattermost-serverGo | 10.11.0 ≤ v < 10.11.10, 10.11.0+incompatible ≤ v < 10.11.10+incompatible | 10.11.10, 10.11.10+incompatible |
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