CVE-2026-20796

Mattermost versions 10.11.x = 10.11.9 fail to properly validate channel membership at the time of data retrieval which allows a deactivated user to learn team names they should not have access to via a race condition in the /commonteams API endpoint.. Mattermost Advisory ID: MMSA-2025-00549...

CVE-2026-20796 Time-of-check time-of-use vulnerability in common teams API

Mattermost versions 10.11.x = 10.11.9 fail to properly validate channel membership at the time of data retrieval which allows a deactivated user to learn team names they should not have access to via a race condition in the /commonteams API endpoint.. Mattermost Advisory ID: MMSA-2025-00549...

CVE-2026-20796 Time-of-check time-of-use vulnerability in common teams API

Mattermost versions 10.11.x = 10.11.9 fail to properly validate channel membership at the time of data retrieval which allows a deactivated user to learn team names they should not have access to via a race condition in the /commonteams API endpoint.. Mattermost Advisory ID: MMSA-2025-00549...