CVE-2026-9693

Mattermost versions 10.11.x <= 10.11.20, 11.7.x <= 11.7.5 Mattermost fails to remove thread membership records when a user is removed from or leaves a team, which allows a previously removed user who is later re-invited to the team to view private channel thread root post content and metadata via the team threads API.. Mattermost Advisory ID: MMSA-2026-00682

Scoring

Severity

LOW

CVSS base score

3.5

CVSS vector

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

EPSS probability

0.16%

CWE

CWE-459

Published

2026-08-17

Last modified

2026-08-18

Affected products

• Mattermost Mattermost
• Mattermost Mattermost
• Mattermost Mattermost
• Mattermost Mattermost
• Mattermost Mattermost

Weakness type

• CWE-459

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