CVE-2026-9571

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

Scoring

Severity

MEDIUM

CVSS base score

5.9

CVSS vector

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

EPSS probability

0.30%

CWE

CWE-305

Published

2026-07-13

Last modified

2026-07-15

Affected products

• Mattermost Mattermost
• Mattermost Mattermost
• Mattermost Mattermost
• Mattermost Mattermost
• Mattermost Mattermost
• Mattermost Mattermost
• Mattermost Mattermost

Weakness type

• CWE-305

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