A flaw was found in nbdkit due to to improperly caching plaintext state across the STARTTLS encryption boundary. A MitM attacker could use this flaw to inject a plaintext NBD_OPT_STRUCTURED_REPLY before proxying everything else a client sends to the server, potentially leading the client to terminate the NBD session. The highest threat from this vulnerability is to system availability.
Exploitability
AV:NAC:HPR:LUI:NScope
S:UImpact
C:NI:NA:L3.1/CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:LOther