Mattermost fails to check if a custom emoji reaction exists when sending it to a post and to limit the amount of custom emojis allowed to be added in a post, allowing an attacker sending a huge amount of non-existent custom emojis in a post to crash the mobile app of a user seeing the post and to crash the server due to overloading when clients attempt to retrive the aforementioned post.
{ "cpes": [ "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*" ], "severity": "Medium" }