Vulnerability identifier: #VU11373

Vulnerability risk: Medium

CVSSv3.1: 7.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2018-0189

CWE-ID: CWE-399

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Cisco IOS XE
Operating systems & Components / Operating system

Vendor: Cisco Systems, Inc

Description
The vulnerability allows a remote unauthenticated attacker to cause DoS condition on the target system.

The weakness exists in the Forwarding Information Base (FIB) code due to a limitation in the way the FIB is internally representing recursive routes. A remote attacker can inject routes into the routing protocol that have a specific recursive pattern and cause the service to crash.

Mitigation
Update to versions 15.6(2)SP1, 15.5(3)S5, 15.4(3)S7, 16.4.2, 16.4.1, 16.3.3, 11.3.3, 16.5(0.13), 16.4.2, 16.4.1, 16.4(0.187), 16.3.3, 16.3(1.81), 15.7(3.1.8A)OT, 15.7(3.1.4A)OT, 15.7(0.2)M, 15.6(3)M1, 15.6(3.0p)M, 15.6(2)T2, 15.6(1)S4.2, 15.6(1)S2.18, 15.6(1.17)S0.47, 15.6(1.9)SP1, 15.5(4)IA1.1, 15.5(3)S4.1, 15.5(3)M5, 15.5(3)M4.1, 15.5(0)IA101.142, 15.4(3)S6.2, 15.4(3)S6.1, 15.4(3)M7, 15.4(1)SY2, 15.4(1)IA1.201, 15.2(6.3.0i)E, 15.2(5)EX, 15.2(5)E2, 15.2(5)E1, 15.2(5.8.1)EA, 15.2(5.7.2)EA, 15.2(5.6.56)EA, 15.2(5.4.1i)E2, 15.2(5.3.29i)E1, 15.2(5.3.27i)E1, 15.2(4)EA6, 15.2(4)E5, 15.2(4.6.22)EA5, 15.2(1)SY6, 15.2(1)SY5.105 or 11.3(3).

Vulnerable software versions

Cisco IOS XE: 15.4.3 S

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External links
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-FIB-dos

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

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