Cisco IOS Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition. Updates are not available.
A vulnerability in IPSec tunnel implementation of Cisco IOS Software could allow an unauthenticated, remote attacker to change the tunnel MTU or path MTU and potentially cause IPSec tunnels to drop.
The vulnerability is due to incorrect processing of certain ICMP packets. An attacker could exploit this vulnerability by sending specific ICMP packets to an affected device in order to change the configured MTU value of the tunnel interface. An exploit could allow the attacker to change the tunnel MTU or path MTU and potentially cause IPSec tunnels to drop.
Cisco has confirmed the vulnerability in a security notice; however, software updates are not available.
At the time this alert was first published, Cisco IOS Software Releases 15.2(4)M and prior were vulnerable. Later releases of Cisco IOS Software may also be vulnerable.
To exploit this vulnerability, the attacker may need access to trusted, internal networks, in which the targeted device may reside, to send specific ICMP packets to be processed by the device. This access requirement could limit the possibility 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.
Cisco has released a security notice at the following link: CVE-2013-6694
Customers are advised to consult Cisco bug ID CSCul29918 for the most complete list of affected product versions.
An unauthenticated, remote attacker could exploit this vulnerability to cause IPSec tunnels to drop, which could lead to a DoS condition.
The vulnerability is due to incorrect processing of certain ICMP packets by the affected software.
An unauthenticated, remote attacker could exploit this vulnerability by sending specific ICMP packets to an affected device designed to change the configured MTU value of the tunnel interface. An exploit could allow the attacker to change the tunnel MTU or path MTU and potentially cause IPSec tunnels to drop, resulting in DoS condition.
Administrators are advised to contact the vendor regarding future updates and releases.
Administrators are advised to allow only trusted users to have network access.
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.
The security vulnerability applies to the following combinations of products.
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