CVE-2026-18795 — Missing server side validation allowed user to quarantine a DM and GM post

CVE-2026-18795

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

Description (CNA)

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

Affected (CNA)

Vendor / product	Versions
Mattermost / Mattermost	affected 11.10.0 through 11.10.0; affected 11.7.0 through 11.7.9; affected 11.9.0 through 11.9.1; affected 11.8.0 through 11.8.5; unaffected 11.11.0; unaffected 11.10.1; unaffected 11.7.10; unaffected 11.9.2; unaffected 11.8.6

CWE

CWE-862

References

https://mattermost.com/security-updates

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.