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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 Mattermost fails to require role-management authorization when setting the scheme_admin flag on group syncable link and patch endpoints, which allows a user with group-link permissions to escalate themselves and group members to team or channel admin via crafted API requests.. Mattermost Advisory ID: MMSA-2026-00665

PUBLISHED Reserved 2026-04-29 | Published 2026-06-12 | Updated 2026-06-12 | Assigner Mattermost




HIGH: 8.8CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Problem types

CWE-863: Incorrect Authorization

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

winfunc finder

References

mattermost.com/security-updates (MMSA-2026-00665) vendor-advisory

cve.org (CVE-2026-7387)

nvd.nist.gov (CVE-2026-7387)

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