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 prevent rendering of external SVGs on link embeds which allows unauthenticated users to crash the Mattermost webapp and desktop app via creating an issue or PR on GitHub.. Mattermost Advisory ID: MMSA-2026-00595
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 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Go | github.com/mattermost/mattermost-server | >= 10.11.0-rc1+incompatible, < 10.11.2+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 | 10.11.2+incompatible, 11.2.4+incompatible, 11.3.2+incompatible, 11.4.1+incompatible | GO-2026-5245 |
| Go | github.com/mattermost/mattermost-server/v5 | all versions | — | GO-2026-5245 |
| Go | github.com/mattermost/mattermost-server/v6 | all versions | — | GO-2026-5245 |
| Go | github.com/mattermost/mattermost/server/v8 | >= 11.4.0-rc1, < 11.4.1 | 11.4.1 | GHSA-86vc-mg26-fj6x |
| Go | github.com/mattermost/mattermost/server/v8 | >= 11.3.0-rc1, < 11.3.2 | 11.3.2 | GHSA-86vc-mg26-fj6x |
| Go | github.com/mattermost/mattermost/server/v8 | >= 11.2.0-rc1, < 11.2.4 | 11.2.4 | GHSA-86vc-mg26-fj6x |
| Go | github.com/mattermost/mattermost/server/v8 | >= 8.0.0-20260105080200-d27a2195068d, < 8.0.0-20260217110922-b7d4a1f1f59b | 8.0.0-20260217110922-b7d4a1f1f59b | GHSA-86vc-mg26-fj6x |
| Go | github.com/mattermost/mattermost/server/v8 | >= 10.11.0-rc1, < 10.11.2 | 10.11.2 | GHSA-86vc-mg26-fj6x |
Advisories 1
- openSUSE-SU-2026:21483-1 Security update for govulncheck-vulndb SUSE / openSUSE Security Updates · Jul 31, 2026
References
- MMSA-2026-00595 vendor-advisory