Mattermost allows members with permission to convert public channels to private and convert private to publicGHSA-h5v9-xw2g-7hrq
MEDIUMGHSA-h5v9-xw2g-7hrq is a medium-severity (CVSS 5.4) CWE-863 vulnerability in github.com/mattermost/mattermost/server/v8. A fix is available for github.com/mattermost/mattermost/server/v8 — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-h5v9-xw2g-7hrq.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
github.com/mattermost/mattermost/server/v8🐹github.com/mattermost/mattermost/server/v8🐹github.com/mattermost/mattermost/server/v8🐹github.com/mattermost/mattermost-server🐹github.com/mattermost/mattermost/server/v8Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Mattermost versions 10.4.x <= 10.4.2, 10.3.x <= 10.3.3, 9.11.x <= 9.11.8 fail to fail to enforce channel conversion restrictions, which allows members with permission to convert public channels to private ones to also convert private ones to public
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/mattermost/mattermost/server/v8 | ≥ 10.4.0&&< 10.4.3 | 10.4.3go get github.com/mattermost/mattermost/server/v8@v10.4.3 |
| 🐹Go | github.com/mattermost/mattermost/server/v8 | ≥ 10.3.0&&< 10.3.4 | 10.3.4go get github.com/mattermost/mattermost/server/v8@v10.3.4 |
| 🐹Go | github.com/mattermost/mattermost/server/v8 | ≥ 9.11.0&&< 9.11.9 | 9.11.9go get github.com/mattermost/mattermost/server/v8@v9.11.9 |
| 🐹Go | github.com/mattermost/mattermost-server | all versions | 9.11.9go get github.com/mattermost/mattermost-server@v9.11.9 |
| 🐹Go | github.com/mattermost/mattermost/server/v8 | all versions | 8.0.0-20250218135018-e644e3c8e393go get github.com/mattermost/mattermost/server/v8@v8.0.0-20250218135018-e644e3c8e393 |
Affected Products
mattermost servermattermostDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/mattermost/mattermost/server/v8, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/mattermost/mattermost/server/v8 to 10.4.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-h5v9-xw2g-7hrq is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.
Frequently Asked Questions
Is GHSA-h5v9-xw2g-7hrq in your dependencies?
Find it across Go, including transitive dependencies.