Goodafternoon, ispconfig make use of memcached but an older version. i want to update this through ispconfig. is it possible to update memcached on this way ? this bug is fixed is version 1.5.6
You mean memcached from Debian? It's installed and run at localhost only, can't be used in ddos as is.
Beside what @elmacus already pointed out, Linux distributuions like Debian patch packages to fix bugs without increasing the software version number, so you can assume that this bug is already fixed in the version that ships with debian if it is critical.