Description
Mattermost versions 10.10.x <= 10.10.1 fail to properly sanitize user data during shared channel membership synchronization, which allows malicious or compromised remote clusters to access sensitive user information via unsanitized user objects. This vulnerability affects Mattermost Server instances with shared channels enabled.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mattermost | Mattermost | 10.10.0 – ≤ 10.10.1 | 10.11.0 |
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.
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP6 | govulncheck-vulndb | 0.0.20250918T182144-150000.1.107.1 | SUSE-SU-2025:03289-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | govulncheck-vulndb | 0.0.20250917T170349-1.1 | openSUSE-SU-2025:15564-1 |
| openSUSE Leap 16.0 | govulncheck-vulndb | 0.0.20260723T184607-160000.1.1 | openSUSE-SU-2026:21483-1 |
| openSUSE Leap 15.6 | govulncheck-vulndb | 0.0.20250918T182144-150000.1.107.1 | SUSE-SU-2025:03289-1 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Go | github.com/mattermost/mattermost-server | >= 10.10.0, < 10.10.2 | 10.10.2 | GHSA-3vcm-c42p-3hhf |
| Go | github.com/mattermost/mattermost-server | >= 10.10.0+incompatible, < 10.10.2+incompatible | 10.10.2+incompatible | GO-2025-3950 |
| Go | github.com/mattermost/mattermost-server/v5 | all versions | — | GO-2025-3950 |
| Go | github.com/mattermost/mattermost-server/v6 | all versions | — | GO-2025-3950 |
| Go | github.com/mattermost/mattermost/server/v8 | < 8.0.0-20250729073403-517ae758cd02 | 8.0.0-20250729073403-517ae758cd02 | GHSA-3vcm-c42p-3hhf |
| Go | github.com/mattermost/mattermost/server/v8 | all versions | — | GO-2025-3950 |
Advisories 4
- openSUSE-SU-2026:21483-1 Security update for govulncheck-vulndb SUSE / openSUSE Security Updates · Jul 31, 2026
- openSUSE-SU-2025:15564-1 govulncheck-vulndb-0.0.20250917T170349-1.1 on GA media SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2025:03289-1 Security update for govulncheck-vulndb SUSE / openSUSE Security Updates · Feb 4, 2026
- WID-SEC-2025-1856 Mattermost Server: Mehrere Schwachstellen BSI CERT-Bund (WID) · Sep 22, 2025