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Description

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

PUBLISHED Reserved 2026-03-02 | Published 2026-06-12 | Updated 2026-06-12 | Assigner Mattermost




MEDIUM: 4.3CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Problem types

CWE-200 Exposure of Sensitive Information to an Unauthorized Actor

Product status

Default status
unaffected

11.6.0 (semver)
affected

11.5.0 (semver)
affected

10.11.0 (semver)
affected

10.11.0 (semver)
affected

11.7.0
unaffected

11.6.2
unaffected

11.5.5
unaffected

10.11.16
unaffected

10.11.17
unaffected

Credits

0x7oda7123 finder

References

mattermost.com/security-updates (MMSA-2026-00616) vendor-advisory

cve.org (CVE-2026-3433)

nvd.nist.gov (CVE-2026-3433)

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