cisco-sa-20190807-iosxr-isis-dos-1918: Cisco IOS XR Software Intermediate System-to-Intermediate System Denial of Service Vulnerability
First published: Wed Aug 07 2019(Updated: )
A vulnerability in the implementation of Intermediate System-to-Intermediate System (IS-IS) routing protocol functionality in Cisco IOS XR Software could allow an unauthenticated attacker who is in the same IS-IS area to cause a denial of service (DoS) condition. The vulnerability is due to incorrect processing of IS-IS link-state protocol data units (PDUs). An attacker could exploit this vulnerability by sending specific link-state PDUs to an affected system to be processed. A successful exploit could allow the attacker to cause incorrect calculations used in the weighted remote shared risk link groups (SRLG) or in the IGP Flexible Algorithm. It could also cause tracebacks to the logs or potentially cause the receiving device to crash the IS-IS process, resulting in a DoS condition. 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://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190807-iosxr-isis-dos-1918 A companion advisory is available at the following link: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190807-iosxr-isis-dos-1910
Credit: This vulnerability was found during the resolution a Cisco TAC support case
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Cisco IOS XRv 9000 | =6.6.1<AA15881=6.5.3<AA15778 | AA15881 AA15778 |
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Reference Links
Frequently Asked Questions
What is the severity of cisco-sa-20190807-iosxr-isis-dos-1918?
The severity of cisco-sa-20190807-iosxr-isis-dos-1918 is classified as high due to its potential to cause a denial of service allowing attackers to disrupt network services.
How do I fix cisco-sa-20190807-iosxr-isis-dos-1918?
To fix cisco-sa-20190807-iosxr-isis-dos-1918, upgrade to the recommended versions of Cisco IOS XR software as specified in the advisory.
What systems are affected by cisco-sa-20190807-iosxr-isis-dos-1918?
Cisco IOS XR version 6.6.1 and 6.5.3 are affected by cisco-sa-20190807-iosxr-isis-dos-1918.
Who can exploit cisco-sa-20190807-iosxr-isis-dos-1918?
An unauthenticated attacker within the same IS-IS area can exploit cisco-sa-20190807-iosxr-isis-dos-1918.
What is the impact of cisco-sa-20190807-iosxr-isis-dos-1918?
The impact of cisco-sa-20190807-iosxr-isis-dos-1918 is a denial of service condition which can disrupt normal operation of affected network devices.
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