CVSS 5.0 (medium) · published 2026-10-16
Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to validate the invited recipient's email address when redeeming team and guest invitation tokens, which allows an authenticated attacker to join a team or gain unauthorized access to private channels via a forwarded or leaked invitation link.. Mattermost Advisory ID: MMSA-2026-00747
Affected products (NVD): mattermost mattermost_server
Fixed in (NVD): 11.7.10, 11.8.6, 11.9.2
Weakness: CWE-863
Source: NVD CVE-2026-18223
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