When running in a High Availability configuration, Mattermost fails to sanitize some of the user_updated and post_deleted events broadcast to all users, leading to disclosure of sensitive information to some of the users with currently connected Websocket clients.

Mattermost allows an attacker to request a preview of an existing message when creating a new message via the createPost API call, disclosing the contents of the linked message.

An issue was discovered in Mattermost Server before 3.0.0. It potentially allows attackers to obtain sensitive information (credential fields within config.json) via the System Console UI.

Mattermost fails to properly authorize the requests fetching team associated AD/LDAP groups, allowing a user to fetch details of AD/LDAP groups of a team that they are not a member of. 

Mattermost versions 10.5.x <= 10.5.6, 10.8.x <= 10.8.1, 10.7.x <= 10.7.3, 9.11.x <= 9.11.16 fail to verify authorization when retrieving cached posts by PendingPostID which allows an authenticated user to read posts in private channels they don't have access to via guessing the PendingPostID of recently created posts.

Mattermost versions 10.4.x <= 10.4.1, 9.11.x <= 9.11.7, 10.3.x <= 10.3.2, 10.2.x <= 10.2.2 fail to properly validate input when patching and duplicating a board, which allows a user to read any arbitrary file on the system via duplicating a specially crafted block in Boards.

Mattermost fails to check channel membership when accessing message threads, allowing an attacker to access arbitrary posts by using the message threads API.

Mattermost fails to sanitize code permalinks, allowing an attacker to preview code from private repositories by posting a specially crafted permalink on a channel.

A missing permissions check in the /plugins/playbooks/api/v0/runs API in Mattermost allows an attacker to list and view playbooks belonging to a team they are not a member of.

Mattermost fails to perform authorization checks in the /plugins/playbooks/api/v0/runs/add-to-timeline-dialog endpoint of the Playbooks plugin allowing an attacker to get limited information about a post if they know the post ID

Mattermost fails to sanitize post metadata during audit logging resulting in permalinks contents being logged

Unrestricted information disclosure of all users in Mattermost version 6.7.0 and earlier allows team members to access some sensitive information by directly accessing the APIs.

Mattermost 6.3.0 and earlier fails to protect email addresses of the creator of the team via one of the APIs, which allows authenticated team members to access this information resulting in sensitive & private information disclosure.

Mattermost fails to sanitize ephemeral error messages, allowing an attacker to obtain arbitrary message contents by a specially crafted /groupmsg command.

An issue was discovered in Mattermost Server before 5.9.0, 5.8.1, 5.7.3, and 4.10.8. It allows attackers to obtain sensitive information during user activation/deactivation.

Mattermost 6.1 and earlier fails to sufficiently validate permissions while viewing archived channels, which allows authenticated users to view contents of archived channels even when this is denied by system administrators by directly accessing the APIs.

Mattermost Desktop fails to correctly handle permissions or prompt the user for consent on certain sensitive ones allowing media exploitation from a malicious mattermost server

Mattermost Desktop App versions <=5.8.0 fail to sufficiently configure Electron Fuses which allows an attacker to gather Chromium cookies or abuse other misconfigurations via remote/local access.

Mattermost Desktop App versions <=5.7.0 fail to correctly prompt for permission when opening external URLs which allows a remote attacker to force a victim over the Internet to run arbitrary programs on the victim's system via custom URI schemes.

Mattermost Desktop App versions <=5.7.0 fail to disable certain Electron debug flags which allows for bypassing TCC restrictions on macOS.

Mattermost versions 9.9.x <= 9.9.1, 9.5.x <= 9.5.7, 9.10.x <= 9.10.0 and 9.8.x <= 9.8.2 fail to ensure that remote/synthetic users cannot create sessions or reset passwords, which allows the munged email addresses, created by shared channels, to be used to receive email notifications and to reset passwords, when they are valid, functional emails.

A Protection Mechanism Failure vulnerability in the REST API of Juniper Networks Contrail Service Orchestration allows one tenant on the system to view confidential configuration details of another tenant on the same system. By utilizing the REST API, one tenant is able to obtain information on another tenant's firewall configuration and access control policies, as well as other sensitive information, exposing the tenant to reduced defense against malicious attacks or exploitation via additional undetermined vulnerabilities. This issue affects Juniper Networks Contrail Service Orchestration versions prior to 6.1.0 Patch 3.