Cisco IOS Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device.
The vulnerability is due to the processing of ICMPv6 packets by an affected device. An unauthenticated, remote attacker could exploit this vulnerability by sending ICMPv6 packets to a vulnerable device. If successful, the attacker could cause the device to reload, resulting in a DoS condition.
Cisco has confirmed this vulnerability in a security advisory and has released updated software.
Indicators of Compromise
Cisco has published a list of affected Cisco IOS Software releases in the security advisory. The Vendor Announcements section of this alert contains a link to the advisory.
The vulnerability is triggered when the affected software processes a valid IPv6 packet sent to a targeted device when the Multiprotocol Label Switching (MPLS) TTL has expired. This action may cause the device to crash.
An unauthenticated, remote attacker could exploit this vulnerability by sending valid IPv6 packets to a targeted device. This action could result in the device reloading, causing a DoS condition. If the attack is repeated, a sustained DoS condition could occur.
An attacker would likely need access to an internal, private network to send packets to an affected device. The access requirement could limit the possibility of a possible attack.
A packet used to exploit this vulnerability would not affect Cisco IOS Software if it was received by an interface where the packet did not have an MPLS label.
Cisco indicates through the CVSS score that functional exploit code exists; however, the code is not known to be publicly available.
Administrators are advised to apply the appropriate updates.
Administrators are advised to allow only trusted users to have network access.
Administrators are advised to implement an intrusion prevention system (IPS) or intrusion detection system (IDS) to help detect and prevent attacks that attempt to exploit this vulnerability.
Administrators are advised to monitor affected systems.
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 e-mail at firstname.lastname@example.org.
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Cisco Multivendor Vulnerability Alerts respond to vulnerabilities identified in third-party vendors' products. These alerts contain information compiled from diverse sources and provide comprehensive technical descriptions, objective analytical assessments, workarounds and practical safeguards, and links to vendor advisories and patches.