{"id":"CVE-2026-3433","aliases":["GHSA-rp4v-qc77-phm4"],"title":"Mattermost doesn't restrict role_updated websocket event broadcasts to members of the affected team or channel","summary":"Mattermost doesn't restrict role_updated websocket event broadcasts to members of the affected team or channel","severity":"medium","cvss":4.3,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","vendor":"mattermost","product":"github.com/mattermost/mattermost-server","ecosystem":"go","affected":["github.com/mattermost/mattermost-server >= 11.6.0, < 11.6.1","github.com/mattermost/mattermost-server >= 11.5.0, < 11.5.5","github.com/mattermost/mattermost-server >= 10.11.0, < 10.11.17","github.com/mattermost/mattermost/server/v8 >= 8.0.0-20250731163400-5b955468ea1e, < 8.0.0-20260504071740-9408b98025d7"],"patched":["github.com/mattermost/mattermost-server 11.6.1","github.com/mattermost/mattermost-server 11.5.5","github.com/mattermost/mattermost-server 10.11.17","github.com/mattermost/mattermost/server/v8 8.0.0-20260504071740-9408b98025d7"],"published":"2026-06-12","updated":"2026-08-24","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-rp4v-qc77-phm4","references":[{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-3433"},{"url":"https://github.com/mattermost/mattermost/pull/35497"},{"url":"https://github.com/mattermost/mattermost/pull/36256"},{"url":"https://github.com/mattermost/mattermost/pull/36257"},{"url":"https://github.com/mattermost/mattermost/pull/36341"},{"url":"https://github.com/mattermost/mattermost/commit/0a0ab0d54d899d308bd1352cc577036917500318"},{"url":"https://github.com/mattermost/mattermost/commit/7425c6817bf244f976c729f8a73cecac8039a1e1"},{"url":"https://github.com/mattermost/mattermost/commit/9408b98025d7364d7dfe7cdb28fcd109b1b595a6"},{"url":"https://github.com/mattermost/mattermost/commit/a30a331a29b9766d46716d4252056d7b74e66da0"},{"url":"https://github.com/mattermost/mattermost"},{"url":"https://github.com/mattermost/mattermost/releases/tag/v10.11.16"},{"url":"https://github.com/mattermost/mattermost/releases/tag/v11.5.5"},{"url":"https://github.com/mattermost/mattermost/releases/tag/v11.6.2"},{"url":"https://github.com/mattermost/mattermost/releases/tag/v11.7.0"},{"url":"https://mattermost.com/security-updates"}],"tags":["osv","go"],"epss":0.0018,"epssPercentile":0.07867,"ingestedAt":"2026-08-25T19:26:23.194Z","slug":"CVE-2026-3433","body":"## Overview\n\nMattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 fail to restrict role_updated websocket event broadcasts to members of the affected team or channel, which allows an authenticated attacker with guest-level access to observe permission scheme change notifications for private teams they are not a member of via the websocket connection. Mattermost Advisory ID: MMSA-2026-00616\n\n## Affected packages\n\n- `github.com/mattermost/mattermost-server >= 11.6.0, < 11.6.1`\n- `github.com/mattermost/mattermost-server >= 11.5.0, < 11.5.5`\n- `github.com/mattermost/mattermost-server >= 10.11.0, < 10.11.17`\n- `github.com/mattermost/mattermost/server/v8 >= 8.0.0-20250731163400-5b955468ea1e, < 8.0.0-20260504071740-9408b98025d7`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `github.com/mattermost/mattermost-server 11.6.1`\n- `github.com/mattermost/mattermost-server 11.5.5`\n- `github.com/mattermost/mattermost-server 10.11.17`\n- `github.com/mattermost/mattermost/server/v8 8.0.0-20260504071740-9408b98025d7`","depth":"sunlit","depthScore":24,"depthScoreParts":{"impact":23.7,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}