A vulnerability in the implementation of the Simple Network Management Protocol (SNMP) IPv4 access control list (ACL) feature of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to perform SNMP polling of an affected device, even if it is configured to deny SNMP traffic.
This vulnerability exists because Cisco IOS Software and Cisco IOS XE Software do not support extended IPv4 ACLs for SNMP, but they do allow administrators to configure extended named IPv4 ACLs that are attached to the SNMP server configuration without a warning message. This can result in no ACL being applied to the SNMP listening process. An attacker could exploit this vulnerability by performing SNMP polling of an affected device. A successful exploit could allow the attacker to perform SNMP operations that should be denied. The attacker has no control of the SNMP ACL configuration and would still need a valid SNMP version 2c (SNMPv2c) community string or SNMP version 3 (SNMPv3) user credentials. SNMP with IPv6 ACL configurations is not affected. For more information, see the section of this advisory.
The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.
Access control involves the use of several protection mechanisms such as:
When any mechanism is not applied or otherwise fails, attackers can compromise the security of the product by gaining privileges, reading sensitive information, executing commands, evading detection, etc. There are two distinct behaviors that can introduce access control weaknesses: