A vulnerability in Hot Standby Router Protocol (HSRP) authentication in the Cisco Nexus series could allow an unauthenticated, adjacent attacker to affect the state of HSRP group members and cause black holing of traffic.
The vulnerability is due to incorrect parsing of malformed HSRP packets. An attacker could exploit this vulnerability by sending malformed HSRP packets to bypass HSRP authentication. An exploit could allow the attacker to bypass HSRP authentication and affect the state of active HSRP group members, causing them to go to SPEAK state, which leads to black holing of traffic and causes a denial of service (DoS) condition.
Cisco has confirmed the vulnerability in a security notice; however, software updates are not available.
Although an attacker does not need to authenticate to a targeted device to exploit this vulnerability, the attacker must be on the same collision or broadcast domain of the targeted device. This access requirement may reduce the likelihood 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.
Customers are advised to consult Cisco bug ID CSCup11309 for a complete list of affected product releases.
Vulnerable ProductsAt the time this alert was first published, Cisco NX-OS Software releases 6.2(2a) and prior were vulnerable. Later releases of Cisco NX-OS Software may also be vulnerable.
Products Confirmed Not VulnerableNo other Cisco products are currently known to be affected by these vulnerabilities.
Administrators are advised to contact the vendor regarding future updates and releases.
Administrators are advised to allow only trusted users to have network access.
Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.
Administrators are advised to monitor affected systems.
Software updates are not available.
The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.
To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
Version Description Section Status Date 1.0 Initial Release NA Final 2014-Jun-11
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