Cisco IOS XE Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition. Updates are available.
A vulnerability in the PPTP ALG feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition.
The vulnerability is due to the improper handling of PPTP packets that are being inspected as part of the NAT feature on Cisco IOS XE Software. An attacker could exploit this vulnerability by sending a large number of PPTP packets to traverse a vulnerable system that is configured for NAT.
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 has confirmed the vulnerability in a security advisory and released software updates.
Cisco IOS XE Software versions prior to 3.9.2S are affected.
Only systems performing ALG and NAT inspection are vulnerable to exploitation, likely reducing the number of vulnerable systems in most environments.
An unauthenticated, remote attacker could exploit this vulnerability to cause a vulnerable device to reload, resulting in a DoS condition.
The vulnerability is due to improper processing of PPTP packets by the Cisco IOS XE network address translation (NAT) and application layer gateway (ALG) features.
An unauthenticated, remote attacker could exploit this vulnerability by sending a large series of PPTP packets designed to traverse interfaces on a vulnerable device. The inspection of the PPTP packets could cause the device to reload, resulting in a DoS condition.
Administrators are advised to apply the appropriate updates.
Administrators can help protect affected systems from external attacks by using a solid firewall strategy.
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 email at firstname.lastname@example.org.
The security vulnerability applies to the following combinations of products.
Cisco IOS XE Software
3.9S .0, .1
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