CVE-2026-20796lowCWE-367

CVE-2026-20796: low-severity vulnerability in Mattermost

Time-of-check time-of-use vulnerability in common teams API

Published

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8Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 3.1epss 0.2%
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 /common_teams API endpoint.. Mattermost Advisory ID: MMSA-2025-00549
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
Affected products
Mattermost · Mattermost
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