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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 require system-level permission when patching protected default system roles, which allows authenticated users with delegated user-management permissions to escalate privileges by altering built-in role permissions via the role patch API.. Mattermost Advisory ID: MMSA-2026-00656

PUBLISHED Reserved 2026-04-21 | Published 2026-06-12 | Updated 2026-06-13 | Assigner Mattermost




MEDIUM: 6.7CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:L

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

NeganSpl01t finder

References

mattermost.com/security-updates (MMSA-2026-00656) vendor-advisory

cve.org (CVE-2026-6739)

nvd.nist.gov (CVE-2026-6739)

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