CVE-2026-16048 PUBLISHED

Channel member roles accept out-of-scope roles

Assigner: Mattermost
Reserved: 17.07.2026 Published: 17.08.2026 Updated: 17.08.2026

Mattermost versions 11.8.x <= 11.8.2, 11.7.x <= 11.7.6, 10.11.x <= 10.11.21 fail to restrict channel member role assignment to channel-scoped roles which allows a channel administrator to gain additional channel permissions via the channel member roles API.. Mattermost Advisory ID: MMSA-2026-00697

Metrics

CVSS 3.1

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
CVSS Score: 6.3

Attack Vector	Network	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	Low
Privileges Required	Low	Integrity Impact	Low
User Interaction	None	Availability Impact	Low

CVSS 3.1

Product Status

Vendor	Mattermost
Product	Mattermost
Versions	Default: unaffected affected from 11.8.0 to 11.8.2 (incl.) affected from 11.7.0 to 11.7.6 (incl.) affected from 10.11.0 to 10.11.21 (incl.) Version 11.9.0 is unaffected Version 11.8.3 is unaffected Version 11.7.7 is unaffected Version 10.11.22 is unaffected

Solutions

Update Mattermost to versions 11.9.0, 11.8.3, 11.7.7, 10.11.22 or higher.

Credits

LePipouDesBois finder

References

MMSA-2026-00697

Problem Types

CWE-863: Incorrect Authorization CWE