SSH private keys of the "Remote alert handlers (Linux)" rule were exposed in the rule page's HTML source in Checkmk <= 2.4.0p18 and all versions of Checkmk 2.3.0. This potentially allowed unauthorized triggering of predefined alert handlers on hosts where the handler was deployed.
Exploitability
AV:NAC:LAT:PPR:LUI:NVulnerable System
VC:LVI:NVA:NSubsequent System
SC:NSI:LSA:L2.3/CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:L/SA:LOther