An issue was discovered in Mattermost Server before 5.21.0. Socket read operations are not appropriately restricted, which allows attackers to cause a denial of service, aka MMSA-2020-0005.
An issue was discovered in Mattermost Server before 5.20.0. Non-members can receive broadcasted team details via the update_team WebSocket event, aka MMSA-2020-0012.
An issue was discovered in Mattermost Server before 5.19.0. Attackers can discover private channels via the "get channel by name" API, aka MMSA-2020-0004.
An issue was discovered in Mattermost Server before 5.19.0. Attackers can rename a channel and cause a collision with a direct message, aka MMSA-2020-0002.
An issue was discovered in Mattermost Server before 5.18.0. It allows attackers to cause a denial of service (memory consumption) via a large Slack import.