sshd in OpenSSH 4 on Debian GNU/Linux, and the 20070303 OpenSSH snapshot, allows remote authenticated users to obtain access to arbitrary SELinux roles by appending a :/ (colon slash) sequence, followed by the role name, to the username.
https://www.exploit-db.com/exploits/6094
https://exchange.xforce.ibmcloud.com/vulnerabilities/44037