CVE-2026-3473mediumCWE-639

CVE-2026-3473: medium-severity vulnerability in Mattermost

Improper file ownership validation in the Boards API allows unauthorised file access

Published

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13Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 5.9epss 0.1%
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
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N
Affected products
Mattermost · Mattermost
Related CVEs — Mattermost

In the same product, most dangerous first.

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