CVE-2026-9571

What it is

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

At a glance

Exploitability

Can be exploited over the network with an admin-level account. High risk of data exposure, data tampering.

Exploit odds

0.3% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-07-13 09:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-07-15 05:17 UTC Last updatedMost recent change to the record

Details

Published

2026-07-13 09:16 UTC

Last modified

2026-07-15 05:17 UTC

Exploit probability

0.3% · EPSS, next 30 days

Weakness

CWE-305

Record status

Analyzed

Affected

• Mattermost Server < 10.11.20
• Mattermost Server < 11.6.5
• Mattermost Server < 11.7.3

Attack profile CVSS 3.1 · 5.9

Attack vector

Network

Complexity

High

Privileges needed

High

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

None