Description
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 Fail to enforce slash command trigger-word uniqueness during command updates which allows an authenticated team member with Manage Own Slash Commands permission to hijack and impersonate existing system or custom slash commands via editing their own slash command trigger to an already-registered trigger through the command update API. Mattermost Advisory ID: MMSA-2026-00597
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mattermost | Mattermost | 11.5.0 – ≤ 11.5.1, 10.11.0 – ≤ 10.11.13, 11.4.0 – ≤ 11.4.3 | 11.6.0 |
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 | < 5.3.2-0.20260306123948-f5fe8ded6b63 | 5.3.2-0.20260306123948-f5fe8ded6b63 | GHSA-wvcv-9xpm-7mqc |
| Go | github.com/mattermost/mattermost-server | >= 10.11.0+incompatible, < 10.11.14+incompatible · >= 11.4.0+incompatible, < 11.4.4+incompatible · >= 11.5.0+incompatible, < 11.5.2+incompatible | 10.11.14+incompatible, 11.4.4+incompatible, 11.5.2+incompatible | GO-2026-5726 |
| Go | github.com/mattermost/mattermost-server/v5 | all versions | — | GO-2026-5726 |
| Go | github.com/mattermost/mattermost-server/v6 | all versions | — | GO-2026-5726 |
| Go | github.com/mattermost/mattermost/server/v8 | >= 11.5.0, < 11.5.2 | 11.5.2 | GHSA-wvcv-9xpm-7mqc |
| Go | github.com/mattermost/mattermost/server/v8 | >= 10.11.0, < 10.11.14 | 10.11.14 | GHSA-wvcv-9xpm-7mqc |
| Go | github.com/mattermost/mattermost/server/v8 | >= 11.4.0, < 11.4.4 | 11.4.4 | GHSA-wvcv-9xpm-7mqc |
| Go | github.com/mattermost/mattermost/server/v8 | < 8.0.0-20260306123948-f5fe8ded6b63 | 8.0.0-20260306123948-f5fe8ded6b63 | GHSA-wvcv-9xpm-7mqc |
Advisories 1
- openSUSE-SU-2026:21483-1 Security update for govulncheck-vulndb SUSE / openSUSE Security Updates · Jul 31, 2026
References
- MMSA-2026-00597 vendor-advisory