Description
Mattermost versions 10.5.x <= 10.5.10, 10.11.x <= 10.11.2 fail to properly validate guest user permissions when adding channel members which allows guest users to add any team members to their private channels via the `/api/v4/channels/{channel_id}/members` endpoint
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mattermost | Mattermost | 10.5.0 – ≤ 10.5.10, 10.11.0 – ≤ 10.11.2 | 10.12.0 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | govulncheck-vulndb | 0.0.20251105T184115-1.1 | openSUSE-SU-2025:15710-1 |
| openSUSE Leap 16.0 | govulncheck-vulndb | 0.0.20260723T184607-160000.1.1 | openSUSE-SU-2026:21483-1 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Go | github.com/mattermost/mattermost-server | >= 10.5.0, < 10.5.11 | 10.5.11 | GHSA-424h-xj87-m937 |
| Go | github.com/mattermost/mattermost-server | >= 10.11.0, < 10.11.3 | 10.11.3 | GHSA-424h-xj87-m937 |
| Go | github.com/mattermost/mattermost-server | >= 10.5.0+incompatible, < 10.5.11+incompatible · >= 10.11.0+incompatible, < 10.11.3+incompatible | 10.5.11+incompatible, 10.11.3+incompatible | GO-2025-4030 |
| Go | github.com/mattermost/mattermost-server/v5 | all versions | — | GO-2025-4030 |
| Go | github.com/mattermost/mattermost-server/v6 | all versions | — | GO-2025-4030 |
| Go | github.com/mattermost/mattermost/server/v8 | < 8.0.0-20250820115038-ff30b84049f0 | 8.0.0-20250820115038-ff30b84049f0 | GHSA-424h-xj87-m937 |
Advisories 2
- openSUSE-SU-2026:21483-1 Security update for govulncheck-vulndb SUSE / openSUSE Security Updates · Jul 31, 2026
- openSUSE-SU-2025:15710-1 govulncheck-vulndb-0.0.20251105T184115-1.1 on GA media SUSE / openSUSE Security Updates · Mar 23, 2026