Administrator terminal manipulation via unsanitized post content

Terminal escape injection in affected Mattermost releases allows remote authenticated users to manipulate administrator terminals through crafted posts. The mmctl report-posts output path prints user-controlled post content without neutralizing ANSI or OSC sequences, so the administrator's terminal interprets the content as control instructions. A Mattermost account must first create a malicious post and an administrator must then display it with the affected mmctl command; screen changes, false prompts, and clipboard replacement occur in that terminal.