CVE-2025-9076
Medium
Description
Mattermost versions 10.10.x <= 10.10.1 fail to properly sanitize user data during shared channel membership synchronization, which allows malicious or compromised remote clusters to access sensitive user information via unsanitized user objects. This vulnerability affects Mattermost Server instances with shared channels enabled.
SeverityMedium
CVSS6.5
Exploit probability—
Product
Mattermost Server
PublishedSep 15, 2025
First seenSep 15, 2025
Weakness typeCWE-862Missing authorization
How to fix
Update
- mattermost mattermost_server10.10.2 or later
- github.com/mattermost/mattermost/server/v88.0.0-20250729073403-517ae758cd02 or later
- github.com/mattermost/mattermost-server10.10.2, 10.10.2+incompatible or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| mattermost mattermost_server | 10.10.0 ≤ v < 10.10.2 | 10.10.2 |
| github.com/mattermost/mattermost/server/v8Go | v < 8.0.0-20250729073403-517ae758cd02, No range specified | 8.0.0-20250729073403-517ae758cd02 |
| github.com/mattermost/mattermost-serverGo | 10.10.0 ≤ v < 10.10.2, 10.10.0+incompatible ≤ v < 10.10.2+incompatible | 10.10.2, 10.10.2+incompatible |
| github.com/mattermost/mattermost-server/v5Go | No range specified | — |
| github.com/mattermost/mattermost-server/v6Go | No range specified | — |
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