Description
Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to validate the OAuth token scope on the callback which allows an authenticated Mattermost user to gain access to private repositories via modifying the scope parameter in the GitHub authorization URL.. Mattermost Advisory ID: MMSA-2026-00628
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mattermost | Mattermost | 11.6.0 – ≤ 11.6.0, 11.5.0 – ≤ 11.5.3, 11.4.0 – ≤ 11.4.4, 10.11.0 – ≤ 10.11.14 | 11.7.0 |
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-plugin-github | < 1.0.1-0.20260318132218-6e6b740c4852 | 1.0.1-0.20260318132218-6e6b740c4852 | GHSA-r5vf-grcx-5vqp |
| Go | github.com/mattermost/mattermost-server | >= 11.6.0, < 11.6.1 | 11.6.1 | GHSA-r5vf-grcx-5vqp |
| Go | github.com/mattermost/mattermost-server | >= 11.5.0, < 11.5.4 | 11.5.4 | GHSA-r5vf-grcx-5vqp |
| Go | github.com/mattermost/mattermost-server | >= 11.4.0, < 11.4.5 | 11.4.5 | GHSA-r5vf-grcx-5vqp |
| Go | github.com/mattermost/mattermost-server | >= 10.11.0, < 10.11.15 | 10.11.15 | GHSA-r5vf-grcx-5vqp |
| Go | github.com/mattermost/mattermost-server | >= 10.11.0+incompatible, < 10.11.15+incompatible · >= 11.4.0+incompatible, < 11.4.5+incompatible · >= 11.5.0+incompatible, < 11.5.4+incompatible · >= 11.6.0+incompatible, < 11.6.1+incompatible | 10.11.15+incompatible, 11.4.5+incompatible, 11.5.4+incompatible, 11.6.1+incompatible | GO-2026-5839 |
Advisories 2
- openSUSE-SU-2026:21483-1 Security update for govulncheck-vulndb SUSE / openSUSE Security Updates · Jul 31, 2026
- WID-SEC-2026-1173 Mattermost: Mehrere Schwachstellen ermöglichen nicht spezifizierten Angriff BSI CERT-Bund (WID) · May 25, 2026
References
- MMSA-2026-00628 vendor-advisory