Security release 8.15.7 and 8.14.10 - Mattermost
Blog post detailing Mattermost 3.5.3 security update for 8.15 and below.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Blog post detailing Mattermost 3.5.3 security update for 8.15 and below.