CVE-2026-16047

published 2026-08-17

CVE-2026-16047: Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fail to validate that users have read access to a channel before linking a board to…

Priority P4 27 medium 4.3 CVSS 3.1

AV N AC L PR L UI N S U C L I N A N

Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fail to validate that users have read access to a channel before linking a board to it, which allows an authenticated attacker to discover the membership of private channels on the same team via creating, patching, importing, or bulk-creating boards with an arbitrary channelId. Mattermost Advisory ID: MMSA-2026-00674

Affected

6 ranges

Vendor	Product	Version range	Fixed in
mattermost	mattermost	10.11.0 – 10.11.21	—
mattermost	mattermost	11.7.0 – 11.7.6	—
mattermost	mattermost	11.8.0 – 11.8.3	—
mattermost	mattermost_server	>= 10.11.0 < 10.11.22	10.11.22
mattermost	mattermost_server	>= 11.7.0 < 11.7.7	11.7.7
mattermost	mattermost_server	>= 11.8.0 < 11.8.4	11.8.4

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CWE-862