Cisco IOS/IOS XE/IOS XR/NX-OS Unidirectional Link Detection denial of service

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CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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6.8$0-$5k0.00

A vulnerability has been found in Cisco IOS, IOS XE, IOS XR and NX-OS (Router Operating System) (the affected version is unknown) and classified as critical. This vulnerability affects an unknown functionality of the component Unidirectional Link Detection. The manipulation with an unknown input leads to a denial of service vulnerability. The CWE definition for the vulnerability is CWE-404. As an impact it is known to affect availability. CVE summarizes:

A vulnerability in the Unidirectional Link Detection (UDLD) feature of Cisco FXOS Software, Cisco IOS Software, Cisco IOS XE Software, Cisco IOS XR Software, and Cisco NX-OS Software could allow an unauthenticated, adjacent attacker to cause an affected device to reload. This vulnerability is due to improper input validation of the UDLD packets. An attacker could exploit this vulnerability by sending specifically crafted UDLD packets to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a denial of service (DoS) condition. Note: The UDLD feature is disabled by default, and the conditions to exploit this vulnerability are strict. An attacker must have full control of a directly connected device. On Cisco IOS XR devices, the impact is limited to the reload of the UDLD process.

The weakness was released 09/23/2021 as cisco-sa-ios-nxos-xr-udld-dos-W5hGHgtQ. The advisory is available at tools.cisco.com. This vulnerability was named CVE-2021-34714 since 06/15/2021. The exploitation appears to be easy. The attack can only be done within the local network. No form of authentication is required for a successful exploitation. The technical details are unknown and an exploit is not available. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 10/01/2021). This vulnerability is assigned to T1499 by the MITRE ATT&CK project.

Upgrading eliminates this vulnerability.

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VulDB Meta Base Score: 6.9
VulDB Meta Temp Score: 6.8

VulDB Base Score: 6.5
VulDB Temp Score: 6.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.4
CNA Vector (Cisco Systems, Inc.): 🔒

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfoedit

Class: Denial of service
CWE: CWE-404
ATT&CK: T1499

Local: No
Remote: Partially

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfoedit

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfoedit

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: tools.cisco.com

Timelineinfoedit

06/15/2021 CVE assigned
09/23/2021 +100 days Advisory disclosed
09/23/2021 +0 days VulDB entry created
10/01/2021 +8 days VulDB last update

Sourcesinfoedit

Vendor: https://www.cisco.com/

Advisory: cisco-sa-ios-nxos-xr-udld-dos-W5hGHgtQ
Status: Confirmed

CVE: CVE-2021-34714 (🔒)
scip Labs: https://www.scip.ch/en/?labs.20150108

Entryinfoedit

Created: 09/23/2021 09:18 AM
Updated: 10/01/2021 12:46 PM
Changes: (1) source_cve_nvd_summary
Complete: 🔍

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