An issue was discovered in Mattermost Server before 4.2.0, 4.1.1, and 4.0.5. It allows crafted posts that potentially cause a web browser to hang.

An issue was discovered in Mattermost Server before 4.2.0, 4.1.1, and 4.0.5, when used as an OAuth 2.0 service provider. It mishandles a deny action for a redirection.

An issue was discovered in Mattermost Server before 4.2.0, 4.1.1, and 4.0.5. It allows attackers to add DEBUG lines to the logs via a REST API version 3 logging endpoint.

An issue was discovered in Mattermost Server before 4.2.0, 4.1.1, and 4.0.5. It allows attackers to obtain sensitive information (user statuses) via a REST API version 4 endpoint.

An issue was discovered in Mattermost Server before 4.2.0, 4.1.1, and 4.0.5, when used as an OAuth 2.0 service provider. Sometimes. resource-owner authorization is bypassed, allowing account takeover.

An issue was discovered in Mattermost Server before 4.2.0, 4.1.1, and 4.0.5. Display names allow XSS.

An issue was discovered in Mattermost Server before 4.2.0, 4.1.1, and 4.0.5. E-mail templates can have a field in which HTML content is not neutralized.

An issue was discovered in Mattermost Server before 4.2.0, 4.1.1, and 4.0.5. It allows Phishing because an error page can have a link.

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. It allows an attacker to create a button that, when pressed by a user, launches an API request.

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. An attacker could create fictive system-message posts via webhooks and slash commands, in the v3 or v4 REST API.

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. It allows SQL injection during the fetching of multiple posts.

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. It discloses the team creator's e-mail address to members.

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. It allows a bypass of restrictions on use of slash commands.

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. It allows attackers to gain privileges by accessing unintended API endpoints on a user's behalf.

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. It allows attackers to gain privileges by using a registered OAuth application with personal access tokens.

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2, when serving as an OAuth 2.0 Service Provider. There is low entropy for authorization data.

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. XSS can occur via OpenGraph data.

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. XSS could occur via a goto_location response to a slash command.

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. XSS could occur via the title_link field of a Slack attachment.

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. XSS could occur via the author_link field of a Slack attachment.