libzmq before 4.0.6 and 4.1.x before 4.1.1 allows remote attackers to conduct downgrade attacks and bypass ZMTP v3 protocol security mechanisms via a ZMTP v2 or earlier header.
Exploitability
AV:NAC:MAu:NImpact
C:NI:PA:N4.3/AV:N/AC:M/Au:N/C:N/I:P/A:N