Security Intelligence Operations

Cisco IOS Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition.

The vulnerability affects devices that are running the vulnerable version of IOS Software and have the L2TP management daemon process running. These devices do not properly handle malformed L2TP packets. An attacker could exploit this vulnerability by sending a crafted L2TP packet to an affected device to cause the device to reload, resulting in a DoS condition.

Cisco confirmed this vulnerability in a security advisory and released updated software.

The following versions of Cisco IOS Software are affected:

12.2SE
12.2SG
12.2SRB
12.4MR
12.4SW
12.4T
12.4XJ
12.4XV
12.4XW

An attacker could exploit this vulnerability to cause the device to reload, resulting in a DoS condition. An attacker could repeatedly exploit this flaw to cause an extended DoS condition. Depending on device configurations, an attacker may not require special access to send malicious requests to an affected system, which would allow attackers to exploit this vulnerability from external networks.

Cisco indicated through CVSS scoring the existence of functional exploit code; however, this exploit code is not known to be publicly available.

Cisco has released a security advisory to address Cisco bug ID CSCsh48879 at the following link: cisco-sa-20080924-l2tp