CVE-2026-3473

published 2026-05-22

CVE-2026-3473: Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to validate file ownership and access control, which allows…

Priority P3 44 high 7.1 CVSS 3.1

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

Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to validate file ownership and access control, which allows an authenticated user to access and download files belonging to other users or teams via crafted Boards API requests using valid file IDs.. Mattermost Advisory ID: MMSA-2026-00620

Affected

12 ranges

Vendor	Product	Version range	Fixed in
github.com	mattermost_mattermost-server	>= 10.11.0 < 10.11.15	10.11.15
github.com	mattermost_mattermost-server	>= 11.4.0 < 11.4.5	11.4.5
github.com	mattermost_mattermost-server	>= 11.5.0 < 11.5.4	11.5.4
github.com	mattermost_mattermost-server	>= 11.6.0 < 11.6.1	11.6.1
mattermost	mattermost	10.11.0 – 10.11.14	—
mattermost	mattermost	11.4.0 – 11.4.4	—
mattermost	mattermost	11.5.0 – 11.5.3	—
mattermost	mattermost	11.6.0 – 11.6.0	—
mattermost	mattermost_server	>= 10.11.0 < 10.11.15	10.11.15
mattermost	mattermost_server	>= 11.4.0 < 11.4.5	11.4.5
mattermost	mattermost_server	>= 11.5.0 < 11.5.4	11.5.4
mattermost	mattermost_server	>= 11.6.0 < 11.6.1	11.6.1

CVSS provenance

nvd v3.1 7.1 HIGH CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N

cvelistv5 v3.1 5.9 MEDIUM CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N

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CWE-639