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Cisco Bug: CSCvu54677 - Cisco IOS XR Software Additional Paths Denial of Service Vulnerability

Last Modified

Oct 14, 2020

Products (2)

  • Cisco ASR 9000 Series Aggregation Services Routers
  • Cisco IOS XR Software

Known Affected Releases

5.3.4.ROUT

Description (partial)

Symptom:
A vulnerability in the Border Gateway Protocol (BGP) additional paths feature of Cisco IOS XR Software could allow an unauthenticated, remote attacker to prevent authorized users from monitoring the BGP status and cause the BGP process to stop processing new updates, resulting in a denial of service (DOS) condition.

The vulnerability is due to an incorrect calculation of lexicographical order when displaying additional path information within Cisco IOS XR Software, which causes an infinite loop. An attacker could exploit this vulnerability by sending a specific BGP update from a BGP neighbor peer session of an affected device; an authorized user must then issue a show bgp command for the vulnerability to be exploited. A successful exploit could allow the attacker to prevent authorized users from properly monitoring the BGP status and prevent BGP from processing new updates, resulting in outdated information in the routing and forwarding tables.  

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-bgp-ErKEqAer

Conditions:
At the time of publication, this vulnerability affected Cisco IOS XR Software releases earlier than 7.1.3, 7.2.1, and 7.3.1.

At the time of publication, Cisco IOS XR Software releases 7.1.3, 7.2.1, and 7.3.1 contained the fix for this vulnerability.

A fix will be made available in 7.1.2 which will FCS end of the August 2020.

At the time of publication, the SMUs in the following table were available.
6.5.3	ASR9K	AA17486

Customers who require SMUs for other platforms and releases are advised to contact their support organization.
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