The PPTP server in Astaro Security Linux before 4.024 provides information about its version, which makes it easier for remote attackers to construct specialized attacks.
https://exchange.xforce.ibmcloud.com/vulnerabilities/17959
http://www.astaro.org/showflat.php?Cat=&Number=51459&page=0&view=collapsed&sb=5&o=&fpart=1#51459