Description
Mattermost versions 9.11.x <= 9.11.8 fail to prompt for explicit approval before adding a team admin to a private channel, which team admins to joining private channels via crafted permalink links without explicit consent from them.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mattermost | Mattermost | 9.11.0 – ≤ 9.11.8 | 10.5.0 |
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 | 0.0.20250327T184518-1.1 | openSUSE-SU-2025:14937-1 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Go | github.com/mattermost/mattermost-server | >= 9.11.0+incompatible, < 9.11.9+incompatible | 9.11.9+incompatible | GO-2025-3555 |
| Go | github.com/mattermost/mattermost-server/v5 | all versions | — | GO-2025-3555 |
| Go | github.com/mattermost/mattermost-server/v6 | all versions | — | GO-2025-3555 |
| Go | github.com/mattermost/mattermost/server/v8 | >= 9.11.0, < 9.11.9 | 9.11.9 | GHSA-cw7q-5cgc-h3h9 |
| Go | github.com/mattermost/mattermost/server/v8 | all versions | — | GO-2025-3555 |
Advisories 2
- openSUSE-SU-2025:14937-1 govulncheck-vulndb-0.0.20250327T184518-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- WID-SEC-2025-0410 Mattermost: Mehrere Schwachstellen BSI CERT-Bund (WID) · Apr 10, 2025