Debian LTS: DLA-1974-1: proftpd-dfsg security update
Summary
Due to incorrect handling of overly long commands, a remote
unauthenticated user could trigger a denial-of-service by reaching an
endless loop.
For Debian 8 "Jessie", this problem has been fixed in version
1.3.5e+r1.3.5-2+deb8u4.
We recommend that you upgrade your proftpd-dfsg packages.
Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://wiki.debian.org/LTS