Env:

Zabbix agent2 5.4.10/6.0.0

Windows 2016\2019, Gentoo Linux, Debian 10

Passive agent check mainly used

Steps to reproduce:

1. Upgraded zabbix agent (5.4.10) to zabbix agent2 (5.4.10) on ~600 servers.
2. We've started to see memory leak in zabbix agent2 on some (<10) hosts. Hosts with problem are on different OS (Windows 2016\Windows 2019\Gentoo Linux\Debian).
3. Reinstalled some windows hosts from scratch - memory leak still exists. 
4. With help of the libleak we've identified, that leak probably exists in libcrypto.so (linux version).
5. Disabled agent encryption on problem hosts (from server to agent) - memory leak stops to appear.

Some screens with memory leak:

Portion of libleak output: