Cisco announced the availability of security patches for a critical authentication bypass flaw (CVE-2021-34746) in Enterprise NFV Infrastructure Software (NFVIS) for which proof-of-concept exploit code is already available. An attacker can exploit the issue to bypass authentication and log in as an administrator to the affected device.
By virtualizing and abstracting the network services from the underlying hardware, NFVIS allows virtual network functions (VNFs) to be managed independently and to be provisioned dynamically.
The CVE-2021-34746 flaw was reported by Orange Group security researcher Cyrille Chatras, the issue received a CVSS score of 9.8.
The vulnerability affects the TACACS+ authentication, authorization and accounting (AAA) feature of Enterprise NFVIS, it is due to incomplete validation of user-supplied input when it is passed to an authentication script. Cisco pointed out that there are no workarounds that address this vulnerability.
“A vulnerability in the TACACS+ authentication, authorization and accounting (AAA) feature of Cisco Enterprise NFV Infrastructure Software (NFVIS) could allow an unauthenticated, remote attacker to bypass authentication and log in to an affected device as an administrator.” reads the advisory published by Cisco. “This vulnerability is due to incomplete validation of user-supplied input that is passed to an authentication script. An attacker could exploit this vulnerability by injecting parameters into an authentication request. A successful exploit could allow the attacker to bypass authentication and log in as an administrator to the affected device.”
The vulnerability affects Enterprise NFVIS release 4.5.1 only if the TACACS external authentication method is configured, Cisco fixed it with Enterprise NFVIS releases 4.6.1.
The good news is that Cisco is not aware of attacks in the wild exploit this flaw.
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(SecurityAffairs – hacking, FIN8)