Description
Mattermost versions 11.2.x <= 11.2.2, 10.11.x <= 10.11.10, 11.4.x <= 11.4.0, 11.3.x <= 11.3.1 fail to sanitize user-controlled post content in the mmctl commands terminal output which allows attackers to manipulate administrator terminals via crafted messages containing ANSI and OSC escape sequences that enable screen manipulation, fake prompts, and clipboard hijacking.. Mattermost Advisory ID: MMSA-2026-00599
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mattermost | Mattermost | 11.2.0 – ≤ 11.2.2, 10.11.0 – ≤ 10.11.10, 11.4.0 – ≤ 11.4.0, 11.3.0 – ≤ 11.3.1 | 11.5.0 |
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 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-rc1+incompatible, < 10.11.11+incompatible · >= 11.2.0-rc1+incompatible, < 11.2.3+incompatible · >= 11.3.0-rc1+incompatible, < 11.3.2+incompatible · >= 11.4.0-rc1+incompatible, < 11.4.1+incompatible | 10.11.11+incompatible, 11.2.3+incompatible, 11.3.2+incompatible, 11.4.1+incompatible | GO-2026-5067 |
| Go | github.com/mattermost/mattermost-server/v5 | all versions | — | GO-2026-5067 |
| Go | github.com/mattermost/mattermost-server/v6 | all versions | — | GO-2026-5067 |
| Go | github.com/mattermost/mattermost/server/v8 | >= 11.4.0-rc1, < 11.4.1 | 11.4.1 | GHSA-3439-vqgj-2gcf |
| Go | github.com/mattermost/mattermost/server/v8 | >= 11.3.0-rc1, < 11.3.2 | 11.3.2 | GHSA-3439-vqgj-2gcf |
| Go | github.com/mattermost/mattermost/server/v8 | >= 11.2.0-rc1, < 11.2.3 | 11.2.3 | GHSA-3439-vqgj-2gcf |
| Go | github.com/mattermost/mattermost/server/v8 | >= 10.11.0-rc1, < 10.11.11 | 10.11.11 | GHSA-3439-vqgj-2gcf |
| Go | github.com/mattermost/mattermost/server/v8 | >= 8.0.0-20260105080200-d27a2195068d, < 8.0.0-20260217110922-b7d4a1f1f59b | 8.0.0-20260217110922-b7d4a1f1f59b | GHSA-3439-vqgj-2gcf |
Advisories 1
- openSUSE-SU-2026:21483-1 Security update for govulncheck-vulndb SUSE / openSUSE Security Updates · Jul 31, 2026
References
- MMSA-2026-00599 vendor-advisory