Description
An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. XSS attacks could occur against an OAuth 2.0 allow/deny page.
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 | 0.0.20251209T172047-150000.1.127.1 | SUSE-SU-2025:4395-1 |
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 |
| openSUSE Leap 15.6 | govulncheck-vulndb | 0.0.20251209T172047-150000.1.127.1 | SUSE-SU-2025:4395-1 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Go | github.com/mattermost/mattermost-server | < 4.1.2 | 4.1.2 | GHSA-9x8x-w6g5-hx4w |
| Go | github.com/mattermost/mattermost-server | >= 4.2.0, < 4.2.1 | 4.2.1 | GHSA-9x8x-w6g5-hx4w |
| Go | github.com/mattermost/mattermost-server | >= 4.3.0-rc1, < 4.3.0 | 4.3.0 | GHSA-9x8x-w6g5-hx4w |
| Go | github.com/mattermost/mattermost-server | < 4.1.2+incompatible · >= 4.2.0+incompatible, < 4.2.1+incompatible · >= 4.3.0-rc1+incompatible, < 4.3.0+incompatible | 4.1.2+incompatible, 4.2.1+incompatible, 4.3.0+incompatible | GO-2025-4190 |
Advisories 2
- openSUSE-SU-2026:21483-1 Security update for govulncheck-vulndb SUSE / openSUSE Security Updates · Jul 31, 2026
- SUSE-SU-2025:4395-1 Security update for govulncheck-vulndb SUSE / openSUSE Security Updates · Mar 23, 2026