Zammad 5.3.x (Fixed 5.4.0) is vulnerable to Incorrect Access Control. An authenticated attacker could gain information about linked accounts of users involved in their tickets using the Zammad API.
Mattermost versions 8.1.x before 8.1.11, 9.3.x before 9.3.3, 9.4.x before 9.4.4, and 9.5.x before 9.5.2 fail to authenticate the source of certain types of post actions, allowing an authenticated attacker to create posts as other users via a crafted post action.