Cisco IOS XE Software contains a vulnerability that could allow an unauthenticated remote attacker to cause a DoS condition.
The vulnerability is due to improper handling of specific L2TP packets by Cisco 1000 ASR. An attacker could exploit this vulnerability by sending a large number of specific L2TP packets to a vulnerable system; this vulnerability cannot be triggered by L2TP traffic transiting a vulnerable device.
A successful exploit could allow the attacker to cause a system to reload, resulting in a DoS condition. Repeated exploitation could result in a sustained DoS condition.
Cisco confirmed the vulnerability in a security advisory and released updated software.
Indicators of Compromise
Cisco ASR 1000 Series Aggregation Services Routers running affected releases of Cisco IOS XE Software are affected by this vulnerability.
Cisco has published a list of affected Cisco IOS XE 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 handling of specific L2TP packets by Cisco devices running the affected software. The vulnerability cannot be triggered by L2TP traffic transiting a vulnerable device.
An unauthenticated, remote attacker could exploit this vulnerability by sending a large number of specific L2TP packets to a vulnerable system. If successful, the attacker could cause the targeted device to reload, resulting in a DoS condition.
To exploit this vulnerability, an attacker may need access to a trusted, internal network to send a series of specific L2TP packets to a vulnerable system. This access requirement may reduce the likelihood of a successful exploit.
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.
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.