CVE-2026-6062: Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 Fail to validate channel ownership of an existing subscription…

PriorityP340medium6.4CVSS 3.1

AVNACHPRLUINSUCHILAL

EPSS

0.15%

5.0th percentile

Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 Fail to validate channel ownership of an existing subscription before applying edits which allows an authenticated attacker to hijack subscriptions from channels they have no access to via a crafted PUT request to the subscription edit endpoint.. Mattermost Advisory ID: MMSA-2026-00650

Affected

8 ranges

Vendor	Product	Version range	Fixed in
mattermost	mattermost	10.11.0 – 10.11.17	—
mattermost	mattermost	11.5.0 – 11.5.5	—
mattermost	mattermost	11.6.0 – 11.6.2	—
mattermost	mattermost	11.7.0 – 11.7.0	—
mattermost	mattermost_server	>= 10.11.0 < 10.11.18	10.11.18
mattermost	mattermost_server	>= 11.5.0 < 11.5.6	11.5.6
mattermost	mattermost_server	>= 11.6.0 < 11.6.3	11.6.3
mattermost	mattermost_server	>= 11.7.0 < 11.7.1	11.7.1

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