CVE-2026-9571 | Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.1… | CVSS 5.9 MEDIUM

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

Metadata

CVE ID: CVE-2026-9571
State: PUBLISHED
Assigner: Mattermost
Reserved: 2026-05-26 11:52 UTC
Published: 2026-07-13 07:50 UTC
Last updated: 2026-07-13 07:50 UTC
Primary CWE: CWE-305
CWE-305 – Authentication Bypass by Primary Weakness
Vendor / Product: Mattermost / Mattermost
Sources: cve.org · NVD

Severity & Metrics

5.9 MEDIUM CVSS 3.1

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

Affected products (1)

Vendor	Product	Platform	Versions
Mattermost	Mattermost	—	11.7.0 ≤ 11.7.2, 11.6.0 ≤ 11.6.4, 10.11.0 ≤ 10.11.19, 11.8.0 …

Weakness (CWE)

CWE	Source	Description
CWE-305	cna	CWE-305 – Authentication Bypass by Primary Weakness

CVSS scores (1)

Score	Severity	Version	Source	Vector
5.9	MEDIUM	3.1	cna	CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N

References (1)

MMSA-2026-00680 https://mattermost.com/security-updates