A flaw was found in libssh. A malicious username expanded through %r in ProxyCommand handling can inject shell metacharacters, exposing environment variables and causing unintended shell behavior.
Exploitability
AV:LAC:LPR:LUI:RScope
S:UImpact
C:LI:LA:N3.9/CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N