AV:N/AC:L/Au:N/C:N/I:N/A:P/E:F/RL:OF/RC:C
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A vulnerability in the IP version 6 (IPv6) processing code of Cisco IOS XR Software for Cisco CRS-3 Carrier Routing System could allow an unauthenticated, remote attacker to trigger an ASIC scan of the Network Processor Unit (NPU) and a reload of the line card processing an IPv6 packet.
The vulnerability is due to incorrect processing of an IPv6 packet carrying IPv6 extension headers that are valid but unlikely to be seen during normal operation. An attacker could exploit this vulnerability by sending such an IPv6 packet to an affected device that is configured to process IPv6 traffic. An exploit could allow the attacker to cause a reload of the line card, resulting in a DoS condition.
Cisco has confirmed the vulnerability in a security advisory and released software updates.
To exploit this vulnerability, an attacker may need to acquire additional information about the targeted device, such as whether the device has specific line cards installed and configured to process IPv6 traffic in addition to running an affected release of Cisco IOS XR Software. An attacker cannot exploit this vulnerability if these conditions are not met.
A successful exploit of this vulnerability could cause a widespread availability impact to systems that rely on an affected device for traffic forwarding.
Cisco indicates through the CVSS score that functional exploit code exists; however, the code is not known to be publicly available.
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Cisco has released a security advisory for Cisco bug ID CSCtx03546 at the following link: cisco-sa-20150611-iosxr
Vulnerable Products
Cisco CRS-3 Carrier Routing System running any of the following releases of Cisco IOS XR Software is affected:
- Cisco IOS XR Software Releases 4.0.1, 4.0.2, 4.0.3, and 4.0.4
- Cisco IOS XR Software Releases 4.1.0, 4.1.1, and 4.1.2
- Cisco IOS XR Software Release 4.2.0
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 apply the appropriate updates.
Administrators are advised to allow only trusted users to have network access.
Administrators can help protect affected systems from external attacks by using a solid firewall strategy.
It is critical to prevent unauthorized direct communication to network devices. Restrict network traffic destined for the network infrastructure to protect against reconnaissance and denial of service attacks. For configuration details, see Protecting Your Core: Infrastructure Protection Access Control Lists.
Administrators are advised to monitor affected systems.
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Cisco customers with active contracts can obtain updates through the Software Center at the following link: Cisco. Cisco customers without contracts can obtain upgrades by contacting the Cisco Technical Assistance Center at 1-800-553-2447 or 1-408-526-7209 or via email at tac@cisco.com.
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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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Version Description Section Status Date 1.0 Initial Release NA Final 2015-Jun-11
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