Description
Mattermost versions 10.11.x <= 10.11.6 and Mattermost GitHub plugin versions <=2.4.0 fail to validate plugin bot identity in reaction forwarding which allows attackers to hijack the GitHub reaction feature to make users add reactions to arbitrary GitHub objects via crafted notification posts.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mattermost | Mattermost | 10.11.0 – ≤ 10.11.6 | 11.1.0 |
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 |
| openSUSE Leap 15.6 | govulncheck-vulndb | 0.0.20251230T014957-150000.1.134.1 | SUSE-SU-2026:0037-1 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Go | github.com/mattermost/mattermost | < 10.11.7-0.20251106103514-3b05384dd014 | 10.11.7-0.20251106103514-3b05384dd014 | GHSA-jf5h-xfw4-p8gp |
| Go | github.com/mattermost/mattermost | >= 11.0.0-alpha.1, < 11.1.0 | 11.1.0 | GHSA-jf5h-xfw4-p8gp |
| Go | github.com/mattermost/mattermost | >= 11.0.0-alpha.1+incompatible, < 11.1.0+incompatible | 11.1.0+incompatible | GO-2025-4247 |
| Go | github.com/mattermost/mattermost-plugin-github | < 1.0.1-0.20250829075715-0deffcfc6bee | 1.0.1-0.20250829075715-0deffcfc6bee | GHSA-jf5h-xfw4-p8gp |
| Go | github.com/mattermost/mattermost-server | >= 10.11.0-rc1+incompatible | — | GO-2025-4247 |
| Go | github.com/mattermost/mattermost-server/v5 | all versions | — | GO-2025-4247 |
| Go | github.com/mattermost/mattermost-server/v6 | all versions | — | GO-2025-4247 |
| Go | github.com/mattermost/mattermost/server/v8 | >= 10.11.0-rc1, < 10.11.7-0.20251106103514-3b05384dd014 | 10.11.7-0.20251106103514-3b05384dd014 | GHSA-jf5h-xfw4-p8gp |
| Go | github.com/mattermost/mattermost/server/v8 | all versions | — | GO-2025-4247 |
Advisories 2
- openSUSE-SU-2026:21483-1 Security update for govulncheck-vulndb SUSE / openSUSE Security Updates · Jul 31, 2026
- SUSE-SU-2026:0037-1 Security update for govulncheck-vulndb SUSE / openSUSE Security Updates · Mar 23, 2026