CVE-2026-9693: Mattermost thread memberships persist after team removal, exposing private channel thread metadata on re-invite
Low · CVSS 3.5 (CVSS 3.1)EPSS 0.27%, 19th percentilePublished Updated Assigner: Mattermost
Description
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
Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:N · CWE-459
Tracked companies
Mapped from the CVE’s affected-product data, NVD CPE matches, vendor advisories or package feeds. A mapping means the vendor’s software is named, not that its hosted service was exposed.
Status incidents that name it
No tracked status incident names this CVE.
Affected vendors and products
Mattermost: Mattermost
References
- CVE record on cve.org (opens in new tab)
- NVD entry (opens in new tab)
- mattermost.com/security-updates (opens in new tab)
- CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (opens in new tab)
- This product uses data from the NVD API but is not endorsed or certified by the NVD. (opens in new tab)
- Known Exploited Vulnerabilities catalog from CISA. (opens in new tab)
- EPSS scores from FIRST (Exploit Prediction Scoring System). (opens in new tab)