Vulnerability identifier: #VU56875

Vulnerability risk: Medium

CVSSv3.1: 6.4 [CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-34714

CWE-ID: CWE-20

Exploitation vector: Local network

Exploit availability: No

Vulnerable software:
Cisco FXOS
Operating systems & Components / Operating system
Cisco IOS
Operating systems & Components / Operating system
Cisco IOS XE
Operating systems & Components / Operating system
Cisco IOS XR
Operating systems & Components / Operating system
Cisco NX-OS
Operating systems & Components / Operating system
Cisco UCS
Other software / Other software solutions
Cisco Firepower 4100 Series Next-Generation Firewall
Hardware solutions / Firmware
Cisco Firepower 9300 Security Appliance
Hardware solutions / Security hardware applicances
Cisco MDS 9000 Series Multilayer Switches
Hardware solutions / Routers & switches, VoIP, GSM, etc
Cisco Nexus 3000 Series Switches
Hardware solutions / Routers & switches, VoIP, GSM, etc
Nexus 5500 Platform Switches
Hardware solutions / Routers & switches, VoIP, GSM, etc
Nexus 5600 Platform Switches
Hardware solutions / Routers & switches, VoIP, GSM, etc
Cisco Nexus 6000 Series Switches
Hardware solutions / Routers & switches, VoIP, GSM, etc
Cisco Nexus 7000 Series Switches
Hardware solutions / Routers & switches, VoIP, GSM, etc
Cisco Nexus 9000 Series Switches NX-OS Mode
Hardware solutions / Routers & switches, VoIP, GSM, etc
UCS 6200 Series Fabric Interconnects
Hardware solutions / Routers & switches, VoIP, GSM, etc
UCS 6300 Series Fabric Interconnects
Hardware solutions / Routers & switches, VoIP, GSM, etc
UCS 6400 Series Fabric Interconnects
Hardware solutions / Routers & switches, VoIP, GSM, etc

Vendor: Cisco Systems, Inc

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to insufficient validation of user-supplied input in the Unidirectional Link Detection (UDLD) feature. A remote attacker on the local network can pass specially crafted input to the application and perform a denial of service (DoS) attack.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Cisco FXOS: 2.2 - 2.9

Cisco IOS: 16.12.4

Cisco IOS XE: 16.12.4

Cisco IOS XR: 6.6 - 7.4

Cisco NX-OS: 7.0.3 I7.9

Cisco UCS: 4.0 - 4.2

Cisco Firepower 4100 Series Next-Generation Firewall: All versions

Cisco Firepower 9300 Security Appliance: All versions

Cisco MDS 9000 Series Multilayer Switches: All versions

Cisco Nexus 3000 Series Switches: All versions

Nexus 5500 Platform Switches: All versions

Nexus 5600 Platform Switches: All versions

Cisco Nexus 6000 Series Switches: All versions

Cisco Nexus 7000 Series Switches: All versions

Cisco Nexus 9000 Series Switches NX-OS Mode: All versions

UCS 6200 Series Fabric Interconnects: All versions

UCS 6300 Series Fabric Interconnects: All versions

UCS 6400 Series Fabric Interconnects: All versions

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External links
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-nxos-xr-udld-dos-W5hGHgtQ

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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 local network (LAN).

Is there known malware, which exploits this vulnerability?

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