CVE-2026-9693 — Mattermost thread memberships persist after team removal, exposing private channel thread metadata on re-invite

CVE-2026-9693

Mattermost thread memberships persist after team removal, exposing private channel thread metadata on re-invite PUBLISHED

Description (CNA)

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

Affected (CNA)

Vendor / product	Versions
Mattermost / Mattermost	affected 10.11.0 through 10.11.20; affected 11.7.0 through 11.7.5; unaffected 11.9.0; unaffected 10.11.21; unaffected 11.7.6

CWE

CWE-459

References

https://mattermost.com/security-updates

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.