Mattermost doesn't restrict role_updated websocket event broadcasts to members of the affected team or channel
Mattermost 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
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describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2026-3433US | — | — | ||
Mattermost 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… | ||||
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references
External citations — patches, advisories, analysis.
- https://github.com/mattermost/mattermostPACKAGE
- https://github.com/mattermost/mattermost/commit/0a0ab0d54d899d308bd1352cc577036917500318WEB
- https://github.com/mattermost/mattermost/commit/7425c6817bf244f976c729f8a73cecac8039a1e1WEB
- https://github.com/mattermost/mattermost/commit/9408b98025d7364d7dfe7cdb28fcd109b1b595a6WEB
- https://github.com/mattermost/mattermost/commit/a30a331a29b9766d46716d4252056d7b74e66da0WEB
- https://github.com/mattermost/mattermost/pull/35497WEB
- https://github.com/mattermost/mattermost/pull/36256WEB
- https://github.com/mattermost/mattermost/pull/36257WEB
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