Description
Mattermost versions 11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, 10.11.x <= 10.11.11 fail to rate limit login requests which allows unauthenticated remote attackers to cause denial of service (server crash and restart) via HTTP/2 single packet attack with 100+ parallel login requests.. Mattermost Advisory ID: MMSA-2025-00566
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mattermost | Mattermost | 11.4.0 – ≤ 11.4.0, 11.3.0 – ≤ 11.3.1, 11.2.0 – ≤ 11.2.3, 10.11.0 – ≤ 10.11.11 | 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 |
| openSUSE Leap 15.6 | govulncheck-vulndb | 0.0.20260402T184258-150000.1.158.1 | SUSE-SU-2026:1205-1 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Go | github.com/mattermost/mattermost-server | >= 11.4.0-rc1, < 11.4.1 | 11.4.1 | GHSA-247x-7qw8-fp98 |
| Go | github.com/mattermost/mattermost-server | >= 11.3.0-rc1, < 11.3.2 | 11.3.2 | GHSA-247x-7qw8-fp98 |
| Go | github.com/mattermost/mattermost-server | >= 11.2.0-rc1, < 11.2.4 | 11.2.4 | GHSA-247x-7qw8-fp98 |
| Go | github.com/mattermost/mattermost-server | >= 10.11.0-rc1, < 10.11.12 | 10.11.12 | GHSA-247x-7qw8-fp98 |
| Go | github.com/mattermost/mattermost-server | >= 10.11.0-rc1+incompatible, < 10.11.12+incompatible · >= 11.2.0-rc1+incompatible, < 11.2.4+incompatible · >= 11.3.0-rc1+incompatible, < 11.3.2+incompatible · >= 11.4.0-rc1+incompatible, < 11.4.1+incompatible | 10.11.12+incompatible, 11.2.4+incompatible, 11.3.2+incompatible, 11.4.1+incompatible | GO-2026-4916 |
Advisories 2
- openSUSE-SU-2026:21483-1 Security update for govulncheck-vulndb SUSE / openSUSE Security Updates · Jul 31, 2026
- SUSE-SU-2026:1205-1 Security update for govulncheck-vulndb SUSE / openSUSE Security Updates · Apr 8, 2026
References
- MMSA-2025-00566 vendor-advisory