CVE-2026-9571 — Joshua Nichols

Description

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

CVSS Vector

CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N

Affected Products

mattermost/mattermost_server

References

https://mattermost.com/security-updates

Published: Jul 13, 2026 09:16 UTC Modified: Jul 13, 2026 21:41 UTC