{"id":"GO-2026-5256","revision":"7d7d69b27618401c9da5a65cc0b77be4","records":[{"revision":"7d7d69b27618401c9da5a65cc0b77be4","observedAt":"2026-10-24T13:19:41.952+00:00","statement":{"source":"osv","id":"GO-2026-5256","aliases":["CVE-2026-28759","GHSA-8h9w-w78c-vvr3"],"title":"Mattermost does not verify remote cluster channel access when processing shared channel membership removals in github.com/mattermost/mattermost-server","description":"Mattermost does not verify remote cluster channel access when processing shared channel membership removals 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 v5.3.2-0.20260216150504-8738f8c4b3d4.","state":0,"publishedAt":"2026-06-25T18:43:15+00:00","modifiedAt":"2026-06-25T19:45:26.2206896+00:00","affected":[{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"10.11.0+incompatible"},{"kind":"fixed","version":"10.11.14+incompatible"},{"kind":"introduced","version":"11.4.0+incompatible"},{"kind":"fixed","version":"11.4.4+incompatible"},{"kind":"introduced","version":"11.5.0+incompatible"},{"kind":"fixed","version":"11.5.2+incompatible"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server/v5","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server/v6","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"8.0.0-20260216150504-8738f8c4b3d4"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[],"references":["https://github.com/advisories/GHSA-8h9w-w78c-vvr3","https://nvd.nist.gov/vuln/detail/CVE-2026-28759","https://github.com/mattermost/mattermost/commit/8738f8c4b3d42b2b687a6231e72f313357a2e891","https://mattermost.com/security-updates"],"sourceUrl":"https://osv.dev/vulnerability/GO-2026-5256","license":"OSV · upstream source license applies","key":"osv:GO-2026-5256","identifiers":["GO-2026-5256","CVE-2026-28759","GHSA-8h9w-w78c-vvr3"]},"retained":false,"historicalAffected":[]}],"coverage":[]}