Slack Nebula before 1.9.7 mishandles CIDR in some configurations and thus accepts arbitrary source IP addresses within the Nebula network.
Exploitability
AV:NAC:HPR:LUI:NScope
S:CImpact
C:NI:LA:L4.9/CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:LOther