SNMPv3 HMAC verification in (1) Net-SNMP 5.2.x before 22.214.171.124, 5.3.x before 126.96.36.199, and 5.4.x before 188.8.131.52; (2) UCD-SNMP; (3) eCos; (4) Juniper Session and Resource Control (SRC) C-series 1.0.0 through 2.0.0; (5) NetApp (aka Network Appliance) Data ONTAP 7.3RC1 and 7.3RC2; (6) SNMP Research before 16.2; (7) multiple Cisco IOS, CatOS, ACE, and Nexus products; (8) Ingate Firewall 3.1.0 and later and SIParator 3.1.0 and later; (9) HP OpenView SNMP Emanate Master Agent 15.x; and possibly other products relies on the client to specify the HMAC length, which makes it easier for remote attackers to bypass SNMP authentication via a length value of 1, which only checks the first byte.
CWE-287 - Improper Authentication
Improper (or broken) authentication attacks are widespread, and have accounted for many of the worst data breaches in recent years. Improper authentication attacks are a class of vulnerabilities where an attacker impersonates a legitimate user by exploiting weaknesses in either session management or credential management to gain access to the user’s account. This can result in disclosure of sensitive information, and can lead to system compromise, theft, identity theft, and fraud.