Description
An issue was discovered in Mattermost Server before 4.2.0, 4.1.1, and 4.0.5. It allows crafted posts that potentially cause a web browser to hang.
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 | 0.0.20260114T191543-150000.1.137.1 | SUSE-SU-2026:0142-1 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Go | github.com/mattermost/mattermost-server | < 4.0.5 | 4.0.5 | GHSA-9589-mq83-f749 |
| Go | github.com/mattermost/mattermost-server | >= 4.1.0, < 4.1.1 | 4.1.1 | GHSA-9589-mq83-f749 |
| Go | github.com/mattermost/mattermost-server | >= 4.2.0-rc1, < 4.2.0 | 4.2.0 | GHSA-9589-mq83-f749 |
| Go | github.com/mattermost/mattermost-server | < 4.0.5+incompatible · >= 4.1.0+incompatible, < 4.1.1+incompatible · >= 4.2.0-rc1+incompatible, < 4.2.0+incompatible | 4.0.5+incompatible, 4.1.1+incompatible, 4.2.0+incompatible | GO-2026-4300 |
Advisories 2
- openSUSE-SU-2026:21483-1 Security update for govulncheck-vulndb SUSE / openSUSE Security Updates · Jul 31, 2026
- SUSE-SU-2026:0142-1 Security update for govulncheck-vulndb SUSE / openSUSE Security Updates · Mar 23, 2026