Mikrotik RouterOs before 6.47 (stable tree) in the /ram/pckg/advanced-tools/nova/bin/netwatch process. An authenticated remote attacker can cause a Denial of Service due to a divide by zero error.
https://seclists.org/fulldisclosure/2021/May/11
https://github.com/cq674350529/pocs_slides/blob/master/pocs/MikroTik/vul_netwatch/README.md