Mattermost versions 9.11.x <= 9.11.6 fail to filter out DMs from the deleted channels endpoint which allows an attacker to infer user IDs and other metadata from deleted DMs if someone had manually marked DMs as deleted in the database.

Mattermost Mobile versions <=2.22.0 fail to properly handle posts with attachments containing fields that cannot be cast to a String, which allows an attacker to cause the mobile to crash via creating and sending such a post to a channel.

Mattermost versions 10.2.x <= 10.2.0, 9.11.x <= 9.11.5, 10.0.x <= 10.0.3, 10.1.x <= 10.1.3 fail to properly handle posts with attachments containing fields that cannot be cast to a String, which allows an attacker to cause the webapp to crash via creating and sending such a post to a channel.

Mattermost Mobile versions <= 2.22.0 fail to properly validate the style of proto supplied to an action's style in post.props.attachments, which allows an attacker to crash the mobile via crafted malicious input.

Mattermost Mobile Apps versions <=2.22.0 fail to properly handle specially crafted attachment names, which allows an attacker to crash the mobile app for any user who opened a channel containing the specially crafted attachment

Mattermost Mobile Apps versions <=2.22.0 fail to properly validate post props which allows a malicious authenticated user to cause a crash via a malicious post.

Mattermost versions 10.2.x <= 10.2.0, 9.11.x <= 9.11.5, 10.0.x <= 10.0.3, 10.1.x <= 10.1.3 fail to properly validate post props which allows a malicious authenticated user to cause a crash via a malicious post.

Mattermost versions 10.2.x <= 10.2.0, 9.11.x <= 9.11.5, 10.0.x <= 10.0.3, 10.1.x <= 10.1.3 fail to properly validate post props which allows a malicious authenticated user to cause a crash via a malicious post.

Mattermost Mobile Apps versions <=2.22.0 fail to properly validate post props which allows a malicious authenticated user to cause a crash via a malicious post.

Mattermost versions 10.2.x <= 10.2.0, 9.11.x <= 9.11.5, 10.0.x <= 10.0.3, 10.1.x <= 10.1.3 fail to properly validate the style of proto supplied to an action's style in post.props.attachments, which allows an attacker to crash the frontend via crafted malicious input.