CVE-2026-3473 — Improper file ownership validation in the Boards API allows unauthorised file access
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 u…
Published: 2026-05-22 · CVSS: 5.9 · CVSS 3.1
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
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7