CVE-2026-9693
Mattermost thread memberships persist after team removal, exposing private channel thread metadata on re-invite
CVSS Score
3.5
EPSS Score
0.0%
EPSS Percentile
0th
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
| CWE | CWE-459 |
| Vendor | mattermost |
| Product | mattermost |
| Published | Aug 17, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
Required
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None
Affected Versions
Mattermost / Mattermost
10.11.0 ≤ 10.11.20 11.7.0 ≤ 11.7.5
Credits
kiwi_71