CVE-2026-9571

6.5 mediumEPSS 0.3%

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

Severity

CVSS 3.1

6.5 medium

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

EPSS: 0.3% chance of exploitation in the next 30 days; higher than 23% of CVEs (scores of 2026-10-31)
CWE: CWE-305
Published: 2026-07-13
Modified: 2026-07-15
Record from: the NVD, synced 2026-10-19

Affected

mattermost:mattermost_server

References

https://mattermost.com/security-updates

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