Cisco IOS XR Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition. Updates are available.
Cisco IOS XR Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition.
The vulnerability is due to improper processing of fragmented packets by the following:
Cisco CRS 16-Slot Line Card Chassis Route Processor (RP-A)
Cisco CRS 16-Slot Line Card Chassis Route Processor B (RP-B)
Carrier Routing System (CRS) Performance Route Processor (PRP)
Cisco CRS Distributed Route Processor (DRP-B)
An attacker could exploit this vulnerability by sending fragmented packets to a vulnerable system; this vulnerability cannot be triggered by IP traffic traversing a vulnerable device. An exploit could allow the attacker to cause the packets originating on the Route Processor CPU to stop transmitting to the fabric, resulting in a DoS condition.
This vulnerability can be triggered by both IPv4 and IPv6 traffic and does not require a TCP three-way handshake.
Cisco has confirmed the vulnerability in a security advisory and released software updates.
Cisco IOS XR Software versions 3.8.1 through 4.2.0 are affected.
Only packets sent directly to a targeted device could trigger the vulnerability. Network traffic transiting the device cannot be used to conduct an exploit, limiting the potential sources of exploitation.
An unauthenticated, remote attacker could exploit the vulnerability to cause a targeted device to stop processing network traffic, resulting in a DoS condition.
The vulnerability is due to improper processing of network packets by Cisco IOS XR Software.
An unauthenticated, remote attacker could exploit the vulnerability by sending fragmented packets to a targeted system. The processing of the fragmented packets could cause the device to stop transmitting additional packets, resulting in a DoS condition.
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 email at firstname.lastname@example.org.
The urgency and severity ratings of this alert are not tailored to individual users; users may value alerts differently based upon their network configurations and circumstances. THE ALERT, AND INFORMATION CONTAINED THEREIN, ARE PROVIDED ON AN "AS IS" BASIS AND DO NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE ALERT, AND INFORMATION CONTAINED THEREIN, OR MATERIALS LINKED FROM THE ALERT, IS AT YOUR OWN RISK. INFORMATION IN THIS ALERT AND ANY RELATED COMMUNICATIONS IS BASED ON OUR KNOWLEDGE AT THE TIME OF PUBLICATION AND IS SUBJECT TO CHANGE WITHOUT NOTICE. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE ALERTS AT ANY TIME.