Description
Mattermost versions 10.11.x <= 10.11.3, 10.5.x <= 10.5.11, 10.12.x <= 10.12.0 fail to validate the relationship between the post being updated and the MSTeams plugin OAuth flow which allows an attacker to edit arbitrary posts via a crafted MSTeams plugin OAuth redirect URL.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mattermost | Mattermost | 10.11.0 – ≤ 10.11.3, 10.5.0 – ≤ 10.5.11, 10.12.0 – ≤ 10.12.0 | 11.0.0 |
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 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 | >= 10.11.0, < 10.11.4 | 10.11.4 | GHSA-ff85-qw3h-g9vp |
| Go | github.com/mattermost/mattermost-server | >= 10.5.0, < 10.5.12 | 10.5.12 | GHSA-ff85-qw3h-g9vp |
| Go | github.com/mattermost/mattermost-server | >= 10.12.0, < 10.12.1 | 10.12.1 | GHSA-ff85-qw3h-g9vp |
| Go | github.com/mattermost/mattermost-server | >= 10.5.0+incompatible, < 10.5.12+incompatible · >= 10.11.0+incompatible, < 10.11.4+incompatible · >= 10.12.0+incompatible, < 10.12.1+incompatible | 10.5.12+incompatible, 10.11.4+incompatible, 10.12.1+incompatible | GO-2025-4129 |
| Go | github.com/mattermost/mattermost-server/v5 | all versions | — | GO-2025-4129 |
| Go | github.com/mattermost/mattermost-server/v6 | all versions | — | GO-2025-4129 |
| Go | github.com/mattermost/mattermost/server/v8 | < 8.0.0-20250929212932-a41db04d2746 | 8.0.0-20250929212932-a41db04d2746 | GHSA-ff85-qw3h-g9vp |
Advisories 2
- openSUSE-SU-2026:21483-1 Security update for govulncheck-vulndb SUSE / openSUSE Security Updates · Jul 31, 2026
- WID-SEC-2025-2315 Mattermost Server und Mobile: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 27, 2025