{"schema_version":"1.3.1","id":"GO-2026-4520","modified":"2026-02-23T18:23:12Z","published":"2026-02-23T18:23:12Z","aliases":["CVE-2026-0999","GHSA-3c9r-7f29-qp32"],"summary":"Mattermost fails to properly validate login method restrictions in github.com/mattermost/mattermost-server","details":"Mattermost fails to properly validate login method restrictions in github.com/mattermost/mattermost-server.\n\nNOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions.\n\n(If this is causing false-positive reports from vulnerability scanners, please suggest an edit to the report.)\n\nThe additional affected modules and versions are: github.com/mattermost/mattermost-server/v5 before v5.3.2-0.20251212052346-61651b0df7ea.","affected":[{"package":{"name":"github.com/mattermost/mattermost-server","ecosystem":"Go"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"}]}],"ecosystem_specific":{}},{"package":{"name":"github.com/mattermost/mattermost-server","ecosystem":"Go"},"ranges":[{"type":"SEMVER","events":[{"introduced":"10.11.0+incompatible"}]}],"ecosystem_specific":{}},{"package":{"name":"github.com/mattermost/mattermost-server","ecosystem":"Go"},"ranges":[{"type":"SEMVER","events":[{"introduced":"11.1.0+incompatible"}]}],"ecosystem_specific":{}},{"package":{"name":"github.com/mattermost/mattermost-server","ecosystem":"Go"},"ranges":[{"type":"SEMVER","events":[{"introduced":"11.2.0+incompatible"}]}],"ecosystem_specific":{}},{"package":{"name":"github.com/mattermost/mattermost-server/v5","ecosystem":"Go"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"}]}],"ecosystem_specific":{"custom_ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.3.2-0.20251212052346-61651b0df7ea"}]}]}},{"package":{"name":"github.com/mattermost/mattermost-server/v6","ecosystem":"Go"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"}]}],"ecosystem_specific":{}},{"package":{"name":"github.com/mattermost/mattermost/server/v8","ecosystem":"Go"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"8.0.0-20251212052346-61651b0df7ea"}]}],"ecosystem_specific":{}}],"references":[{"type":"ADVISORY","url":"https://github.com/advisories/GHSA-3c9r-7f29-qp32"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-0999"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/commit/61651b0df7ea5db55d1e54f8d6fb5fce4149309c"},{"type":"WEB","url":"https://mattermost.com/security-updates"}],"database_specific":{"url":"https://pkg.go.dev/vuln/GO-2026-4520","review_status":"UNREVIEWED"}}