Cisco Security Advisory
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AV:A/AC:L/Au:N/C:P/I:N/A:P/E:F/RL:U/RC:C
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A vulnerability in the handling of incoming Layer 2 packets tagged with a Cisco Nexus 9000 Series Switch (N9K) reserved VLAN number could allow an unauthenticated, adjacent attacker to cause a partial denial of service (DoS) condition due to increased CPU utilization and possible control plane instability. In addition, Layer 2 packets, which should be dropped by the switch, may be incorrectly forwarded to the connected interfaces.
The vulnerability is due to lack of validation of the VLAN number in the Layer 2 packet. An attacker could exploit this vulnerability by sending a crafted Layer 2 packet tagged with an N9K reserved VLAN number. An exploit could allow the attacker to cause a partial DoS condition due to increased CPU utilization and possible control plane instability. In addition, this packet should be dropped by the N9K, but could be forwarded to the attached networks.
Cisco has confirmed the vulnerability; however, updates are not available.
To exploit the vulnerability, an unauthenticated attacker would need access to the local network. This restriction reduces the potential for exploitation.
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Cisco has released bug ID CSCuw13560 for registered users, which contains additional details and an up-to-date list of affected product versions.
Vulnerable Products
At the time this alert was first published, Cisco Nexus 9000 Series Software Releases 6.1(2)I3(4) and 7.0(3)I1(1) were vulnerable. Later releases may also be affected.Products Confirmed Not Vulnerable
No other Cisco products are currently known to be affected by these vulnerabilities.
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Administrators are advised to contact the vendor regarding future updates and releases.
Administrators are advised to monitor affected systems.
Administrators are advised to change the reserved VLAN range so that it does not conflict with incoming traffic.
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Updates are not available.
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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.
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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.
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Show LessVersion Description Section Status Date 1.0 Initial Release NA Final 2015-Sep-16
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