CVE-2025-8402 Nil pointer dereference in bulk import crashes server

Mattermost versions 10.8.x = 10.8.3, 10.5.x = 10.5.8, 9.11.x = 9.11.17, 10.10.x = 10.10.0, 10.9.x = 10.9.3 fail to validate import data which allows a system admin to crash the server via the bulk import feature...