CVE-2026-9571

EUVD-2026-43305
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
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
MattermostCNA
5.9 MEDIUM
NETWORK
HIGH
HIGH
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 8%
Affected Products (NVD)
VendorProductVersion
mattermostmattermost_server
10.11.0 ≤
𝑥
< 10.11.20
mattermostmattermost_server
11.6.0 ≤
𝑥
< 11.6.5
mattermostmattermost_server
11.7.0 ≤
𝑥
< 11.7.3
𝑥
= Vulnerable software versions
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
mattermostmattermost
11.7.0 ≤
𝑥
≤ 11.7.2
CNA
mattermostmattermost
11.6.0 ≤
𝑥
≤ 11.6.4
CNA
mattermostmattermost
10.11.0 ≤
𝑥
≤ 10.11.19
CNA