Knot DNS before 2.3.0 allows remote DNS servers to cause a denial of service (memory exhaustion and slave server crash) via a large zone transfer for (1) DDNS, (2) AXFR, or (3) IXFR.
www.openwall.com/lists/oss-security/2016/07/06/3
www.openwall.com/lists/oss-security/2016/07/06/4
www.securityfocus.com/bid/91678
github.com/sischkg/xfer-limit/blob/master/README.md
gitlab.labs.nic.cz/labs/knot/blob/c546a70563ef4c7badb7cb5bdf6d1ba8e7adae82/NEWS
gitlab.labs.nic.cz/labs/knot/issues/464
lists.dns-oarc.net/pipermail/dns-operations/2016-July/015058.html