high
7.4
CWE
20
Advisory Published

cisco-sa-ios-nxos-xr-udld-dos-W5hGHgtQ: Multiple Cisco Operating Systems Unidirectional Link Detection Denial of Service Vulnerability

First published: Wed Sep 22 2021(Updated: )

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. 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-ios-nxos-xr-udld-dos-W5hGHgtQ This advisory is part of the September 2021 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2021 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.

Credit: This vulnerability was found by Marco Cassini Cisco during internal security testing

Affected SoftwareAffected VersionHow to fix
Cisco FX-OS=2.9<2.9.1.135 1=2.8<2.8.1.143 1=2.7<2.7.1.1431=2.6<2.6.1.2241=2.4<2.4.1.2731=2.3<2.3.1.2161=2.2<2.2.2.1481
2.9.1.135 1
2.8.1.143 1
2.7.1.1431
2.6.1.2241
2.4.1.2731
2.3.1.2161
2.2.2.1481
Cisco IOS XRv 9000>=6.6=6.7=6.8=7.2<=7.3<7.3.1, 7.3.15
7.3.1, 7.3.15
Cisco Unified Computing System (UCS)=4.1<4.1(2c)>=Earlier than 4.0<=4.0<4.0(4l)
4.1(2c)
4.0(4l)

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Child vulnerabilities

(Contains the following vulnerabilities)

Frequently Asked Questions

  • What is the vulnerability ID for this Cisco vulnerability?

    The vulnerability ID for this Cisco vulnerability is cisco-sa-ios-nxos-xr-udld-dos-W5hGHgtQ.

  • What is the title of this vulnerability?

    The title of this vulnerability is Multiple Cisco Operating Systems Unidirectional Link Detection Denial of Service Vulnerability.

  • What is the severity of cisco-sa-ios-nxos-xr-udld-dos-W5hGHgtQ?

    The severity of cisco-sa-ios-nxos-xr-udld-dos-W5hGHgtQ is high with a severity value of 7.4.

  • How does the vulnerability affect Cisco FXOS Software?

    The vulnerability affects Cisco FXOS Software versions 2.9, 2.8, 2.7, 2.6, 2.4, 2.3, and 2.2 with specific subversions.

  • How does the vulnerability affect Cisco IOS XR Software?

    The vulnerability affects Cisco IOS XR Software versions 6.6, 6.7, 6.8, 7.2, 7.3 up to 7.3.1 and 7.3.15.

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