GHSA-gq3r-5833-5532 Mattermost Fails to Validate File Paths

• Go github.com/mattermost/mattermost-server: >= 10.9.0, < 10.9.2 → fixed in 10.9.2 • Go github.com/mattermost/mattermost-server: >= 10.8.0, < 10.8.4 → fixed in 10.8.4 • Go github.com/mattermost/mattermost-server: >= 10.5.0, < 10.5.9 → fixed in 10.5.9 • Go github.com/mattermost/mattermost-server: >= 9.11.0, < 9.11.18 → fixed in 9.11.18 • Go github.com/mattermost/mattermost/server/v8: < 8.0.0-20250619095651-9dd0b3943e55 → fixed in 8.0.0-20250619095651-9dd0b3943e55 • Go github.com/mattermost/mattermost-server/v5: <= 5.11.1 (no fix yet) • Go github.com/mattermost/mattermost-server/v6: <= 6.7.2 (no fix yet)

Mattermost versions 10.9.x <= 10.9.1, 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17 fail to properly validate file paths during plugin import operations which allows restricted admin users to install unauthorized custom plugins via path traversal in the import functionality, bypassing plugin signature enforcement and marketplace restrictions.