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.

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. Knowledge of a session ID allows revoking another user's session.

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. XSS attacks could occur against an OAuth 2.0 allow/deny page.

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2 when local storage for files is used. A System Admin can test for the existence of an arbitrary file.

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2 when local storage for files is used. A System Admin can create arbitrary files.

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2 when local storage for files is used. A System Admin can achieve directory traversal.

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. It allows attackers to cause a denial of service (channel invisibility) via a misformatted post.

An issue was discovered in Mattermost Server before 4.4.3 and 4.3.3. Attackers could reconfigure an OAuth app in some cases where Mattermost is an OAuth 2.0 service provider.

An issue was discovered in Mattermost Server before 4.5.0, 4.4.5, 4.3.4, and 4.2.2. It allows attackers to cause a denial of service (application crash) via an @ character before a JavaScript field name.

An issue was discovered in Mattermost Server before 4.5.0, 4.4.5, and 4.3.4. It mishandled webhook access control in the EnableOnlyAdminIntegrations case.