libssh before 0.7.3 improperly truncates ephemeral secrets generated for the (1) diffie-hellman-group1 and (2) diffie-hellman-group14 key exchange methods to 128 bits, which makes it easier for man-in-the-middle attackers to decrypt or intercept SSH sessions via unspecified vectors, aka a "bits/bytes confusion bug."
Exploitability
AV:NAC:HPR:NUI:NScope
S:UImpact
C:HI:NA:N5.9/CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N