GHSA-g7fp-cqj5-x8hf
MEDIUMGHSA-g7fp-cqj5-x8hf is a medium-severity (CVSS 5.4) CWE-863 vulnerability in github.com/mattermost/mattermost/server/v8. O3 Security confirms whether GHSA-g7fp-cqj5-x8hf is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Mattermost has an Incorrect Authorization issue
Blast Radius
github.com/mattermost/mattermost/server/v8🐹github.com/mattermost/mattermost/server/v8🐹github.com/mattermost/mattermost/server/v8🐹github.com/mattermost/mattermost/server/v8🐹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 11.2.x <= 11.2.2, 10.11.x <= 10.11.10, 11.4.x <= 11.4.0, 11.3.x <= 11.3.1 fail to restrict team-level access when processing membership sync from a remote cluster, which allows a malicious remote cluster to grant a user access to an entire private team instead of only the shared channel via sending crafted membership sync messages that trigger team membership assignment. Mattermost Advisory ID: MMSA-2026-00574
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/mattermost/mattermost/server/v8 | ≥ 11.4.0-rc1&&< 11.4.1 | 11.4.1 |
| 🐹Go | github.com/mattermost/mattermost/server/v8 | ≥ 11.3.0-rc1&&< 11.3.2 | 11.3.2 |
| 🐹Go | github.com/mattermost/mattermost/server/v8 | ≥ 11.2.0-rc1&&< 11.2.3 | 11.2.3 |
| 🐹Go | github.com/mattermost/mattermost/server/v8 | ≥ 10.11.0-rc1&&< 10.11.11 | 10.11.11 |
| 🐹Go | github.com/mattermost/mattermost/server/v8 | ≥ 8.0.0-20260105080200-d27a2195068d&&< 8.0.0-20260217110922-b7d4a1f1f59b | 8.0.0-20260217110922-b7d4a1f1f59b |
Detection & 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. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/mattermost/mattermost/server/v8 to 11.4.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-g7fp-cqj5-x8hf is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-g7fp-cqj5-x8hf is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-g7fp-cqj5-x8hf. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-g7fp-cqj5-x8hf in your dependencies?
O3 detects GHSA-g7fp-cqj5-x8hf across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.