Host and event action script input is validated with a regex (set by the administrator), but the validation runs in multiline mode. If ^ and $ anchors are used in user input validation, an injected newline lets authenticated users bypass the check and inject shell commands.
Exploitability
AV:NAC:LAT:PPR:LUI:NVulnerable System
VC:HVI:HVA:HSubsequent System
SC:NSI:NSA:N7.7/CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:NInjection