Cisco Security Advisory
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AV:N/AC:L/Au:N/C:P/I:N/A:N/E:F/RL:OF/RC:C
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A vulnerability in the Zone-Based Firewall feature of Cisco IOS and Cisco IOS XE Software could allow an unauthenticated, remote attacker to pass traffic that should otherwise have been dropped based on the configuration.
The vulnerability is due to a logic flaw in a corner case scenario. An attacker could exploit this vulnerability by sending traffic that would have been dropped by the policy.
In a Zone-Based Firewall setup, if only one zone pair is defined in the egress direction but there is no reverse zone pair defined in the opposite direction, return traffic should be dropped instead of allowed for traffic subject to the egress action of pass.
There are workarounds that address this vulnerability.
This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20161207-ios-zbf
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Administrators may define two zone pairs, one in each direction, to explicitly control traffic between two security zones.
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For information about fixed software releases, consult the Cisco bug ID(s) at the top of this advisory.
When considering software upgrades, customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories and Alerts page, to determine exposure and a complete upgrade solution.
In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.
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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 public release. — Final 2016-December-07
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