CVE-2026-18795

Missing server side validation allowed user to quarantine a DM and GM post

State: Published
Severity: 6.4 Medium
Published: Oct 16, 2026
Updated: Oct 16, 2026
Reserved: Aug 4, 2026

Description

Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to enforce DM/GM check on server side which allows an authenticated user to quarantine a post belonging to DM or GM via direct API call.. Mattermost Advisory ID: MMSA-2026-00756

Scores

CVSS	Score	Vector	Source
3.1	6.4 Medium	CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L	Mattermost

Weaknesses

CWE-862 Missing Authorization

Affected Products

Product	Versions
MattermostMattermost	11.10.0 through 11.10.0Affected 11.7.0 through 11.7.9Affected 11.9.0 through 11.9.1Affected 11.8.0 through 11.8.5Affected 11.11.0Not affected 11.10.1Not affected 11.7.10Not affected 11.9.2Not affected 11.8.6Not affected

References

MMSA-2026-00756vendor-advisory

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