Netatalk before 3.1.12 is vulnerable to an out of bounds write in dsi_opensess.c. This is due to lack of bounds checking on attacker controlled data. A remote unauthenticated attacker can leverage this vulnerability to achieve arbitrary code execution.
https://www.synology.com/security/advisory/Synology_SA_18_62
https://www.debian.org/security/2018/dsa-4356
https://github.com/tenable/poc/tree/master/netatalk/cve_2018_1160/