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Description

Mattermost versions 11.2.x <= 11.2.2, 10.11.x <= 10.11.10, 11.4.x <= 11.4.0, 11.3.x <= 11.3.1 fail to apply view restrictions when retrieving group member IDs, which allows authenticated guest users to enumerate user IDs outside their allowed visibility scope via the group retrieval endpoint.. Mattermost Advisory ID: MMSA-2026-00594

PUBLISHED Reserved 2026-02-24 | Published 2026-03-26 | Updated 2026-03-26 | 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-863: Incorrect Authorization

Product status

Default status
unaffected

11.2.0 (semver)
affected

10.11.0 (semver)
affected

11.4.0 (semver)
affected

11.3.0 (semver)
affected

11.5.0
unaffected

11.2.3
unaffected

10.11.11
unaffected

11.4.1
unaffected

11.3.2
unaffected

Credits

winfunc finder

References

mattermost.com/security-updates (MMSA-2026-00594) vendor-advisory

cve.org (CVE-2026-3115)

nvd.nist.gov (CVE-2026-3115)

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