CVE-2026-10085 PUBLISHED

Ordinary group/direct message member can enable group_constrained and remove all channel participants

Assigner: Mattermost
Reserved: 29.05.2026 Published: 13.07.2026 Updated: 13.07.2026

Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to restrict the group_constrained channel flag to public and private channels that support group synchronization, which allows an ordinary group or direct message member to remove all participants from the conversation via the channel patch API.. Mattermost Advisory ID: MMSA-2026-00688

Metrics

CVSS 3.1

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
CVSS Score: 5.4

Attack Vector	Network	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	None
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 11.7.0 to 11.7.2 (incl.) affected from 11.6.0 to 11.6.4 (incl.) affected from 10.11.0 to 10.11.19 (incl.) Version 11.8.0 is unaffected Version 11.7.3 is unaffected Version 11.6.5 is unaffected Version 10.11.20 is unaffected

Solutions

Update Mattermost to versions 11.8.0, 11.7.3, 11.6.5, 10.11.20 or higher.

Credits

se1en finder

References

MMSA-2026-00688

Problem Types

CWE-862: Missing Authorization CWE