{"id":"CVE-2026-16453","revision":"6469c92bd55c485d8a1c39acaec298d2","records":[{"revision":"6469c92bd55c485d8a1c39acaec298d2","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-16453","aliases":[],"title":"Mattermost SAML RelayState forgery allows unauthorized team membership","description":"Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to verify the integrity of the SAML RelayState POST parameter which allows an authenticated SAML user to join any team, including invite-only teams, via forging the team_id or invite_id fields in the RelayState.. Mattermost Advisory ID: MMSA-2026-00727","state":0,"publishedAt":"2026-10-16T07:08:48.627+00:00","modifiedAt":"2026-10-16T14:18:12.181+00:00","affected":[{"ecosystem":"Vendor product","name":"Mattermost","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"defaultStatus\": \"unaffected\",\n                    \"product\": \"Mattermost\",\n                    \"vendor\": \"Mattermost\",\n                    \"versions\": [\n                        {\n                            \"lessThanOrEqual\": \"11.10.0\",\n                            \"status\": \"affected\",\n                            \"version\": \"11.10.0\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"lessThanOrEqual\": \"11.7.9\",\n                            \"status\": \"affected\",\n                            \"version\": \"11.7.0\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"lessThanOrEqual\": \"11.9.1\",\n                            \"status\": \"affected\",\n                            \"version\": \"11.9.0\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"lessThanOrEqual\": \"11.8.5\",\n                            \"status\": \"affected\",\n                            \"version\": \"11.8.0\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"11.11.0\",\n                            \"status\": \"unaffected\"\n                        },\n                        {\n                            \"version\": \"11.10.1\",\n                            \"status\": \"unaffected\"\n                        },\n                        {\n                            \"version\": \"11.7.10\",\n                            \"status\": \"unaffected\"\n                        },\n                        {\n                            \"version\": \"11.9.2\",\n                            \"status\": \"unaffected\"\n                        },\n                        {\n                            \"version\": \"11.8.6\",\n                            \"status\": \"unaffected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N","score":7.1,"severity":"HIGH"}],"references":["https://mattermost.com/security-updates"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-16453","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-16453","identifiers":["CVE-2026-16453"]},"retained":false,"historicalAffected":[]}],"coverage":[]}