Vulnerability identifier: #VU6987

Vulnerability risk: Low

CVSSv3.1: 5.2 [CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2017-6666

CWE-ID: CWE-20

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Network Convergence System 5500 Series
Hardware solutions / Routers & switches, VoIP, GSM, etc

Vendor: Cisco Systems, Inc

Description
The vulnerability allows local authenticated attacker to cause DoS condition on the target system.

The weakness exists in the forwarding component of Cisco IOS XR Software for Cisco Network Convergence System (NCS) 5500 Series Routers due to adjacency information for a Traffic Engineering (TE) tunnel's physical source interface is not propagated to hardware after the adjacency is lost. A local attacker can log in to the router's CLI with administrator privileges, issue the clear arp-cache command and cause the router to stop forwarding data traffic across Traffic Engineering (TE) tunnels.

Successful exploitation of the vulnerability results in denial of service.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Network Convergence System 5500 Series: 6.2.11.BASE

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External links
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170607-ncs

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.