OPERATIONAL DEFECT DATABASE
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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://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-nxos-xr-udld-dos-W5hGHgtQ
For information on fixed versions of software consult the Cisco IOS Software checker: https://tools.cisco.com/security/center/softwarechecker.x See Vulnerable Products Section of the advisory for full details: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-nxos-xr-udld-dos-W5hGHgtQ#vp
There are no workarounds that address this vulnerability.
Please refer to the Security Advisory.
The Cisco PSIRT has assigned this bug the following CVSS version 3 score. The Base CVSS score as of the time of evaluation is 7.4: https://tools.cisco.com/security/center/cvssCalculator.x?version=3.0&vector=CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H CVE ID CVE-2021-34714 has been assigned to document this issue. Additional information on Cisco's security vulnerability policy can be found at the following URL: https://tools.cisco.com/security/center/resources/security_vulnerability_policy.html
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