As of September 15, 2019, Cisco will no longer publish non-Cisco product alerts for third-party software vulnerabilities. For more information about vulnerabilities in third-party software, see the Cisco Security Vulnerability Policy.
Multivendor Vulnerability Alert
Cisco IOS Software IPv6 Packet Processing Denial of Service Vulnerability
Cisco IOS Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on a targeted device.
The vulnerability is due to improper handling of malformed packets. An unauthenticated, remote attacker could exploit this vulnerability by sending malicious network packets to the device. If successful, the attacker could cause the device to become unresponsive, resulting in a DoS condition.
Cisco confirmed the vulnerability in a security advisory and 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 due to improper processing of malformed IP version 6 (IPv6) packets by Cisco IOS Software.
An unauthenticated, remote attacker could exploit this vulnerability by sending malicious IPv6 packets to a targeted device. When processed, the packets could trigger an error condition on the device, causing the device to fail and reload, resulting in a DoS condition.
Only devices that are configured to process IPv6 network traffic are vulnerable to exploitation. In addition, only network packets that are sent directly to the device, rather than packets that transit device interfaces, could trigger an exploit. Because many configurations block packets that are sent directly to a device, exploitation may be difficult.
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 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.
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 email@example.com.
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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.