CVE-2026-9571 — Deactivated user accounts can continue to obtain valid OAuth access tokens via refresh token grant in Mattermost
Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to invalidate OAuth refresh tokens upon user account deactivation, which allows a deactivated us…
Published: 2026-07-13 · CVSS: 5.9 · CVSS 3.1
Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to invalidate OAuth refresh tokens upon user account deactivation, which allows a deactivated user or an attacker in possession of a valid refresh token to obtain new functional access tokens via the OAuth refresh token grant endpoint.. Mattermost Advisory ID: MMSA-2026-00680
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7