A vulnerability in Cisco Nexus 1000V switches could allow an unauthenticated, remote attacker to bypass deny statements in access control lists (ACLs) with certain types of Internet Group Management Protocol version 2 (IGMPv2) or IGMP version 3 (IGMPv3) traffic. IGMP version 1 (IGMPv1) is not affected.
The vulnerability is due to a lack of IGMPv2 and IGMPv3 support in ACLs. An attacker could exploit this vulnerability by sending certain IGMPv2 or IGMPv3 requests to an affected switch.
Cisco has confirmed the vulnerability in a security notice and released software updates.
To exploit this vulnerability, an attacker may need access to trusted, internal networks to send IGMPv2 or IGMPv3 requests to a targeted device. This access requirement may reduce the possibility of a successful exploit.
Cisco indicates through the CVSS score that functional exploit code exists; however, the code is not known to be publicly available.