A vulnerability in the Unidirectional Link Detection (UDLD) feature of Cisco FXOS Software and Cisco NX-OS Software could allow an unauthenticated, adjacent attacker to execute arbitrary code with administrative privileges or cause a denial of service (DoS) condition on an affected device. This vulnerability is due to insufficient input validation. An attacker could exploit this vulnerability by sending crafted Cisco UDLD protocol packets to a directly connected, affected device. A successful exploit could allow the attacker to execute arbitrary code with administrative privileges or cause the Cisco UDLD process to crash and restart multiple times, causing the affected device to reload and resulting in a DoS condition. Note: The UDLD feature is disabled by default, and the conditions to exploit this vulnerability are strict. The attacker needs full control of a directly connected device. That device must be connected over a port channel that has UDLD enabled. To trigger arbitrary code execution, both the UDLD-enabled port channel and specific system conditions must exist. In the absence of either the UDLD-enabled port channel or the system conditions, attempts to exploit this vulnerability will result in a DoS condition. It is possible, but highly unlikely, that an attacker could control the necessary conditions for exploitation. The CVSS score reflects this possibility. However, given the complexity of exploitation, Cisco has assigned a Medium Security Impact Rating (SIR) to this vulnerability.

A vulnerability in the Unidirectional Link Detection (UDLD) feature of Cisco FXOS Software and Cisco NX-OS Software could allow an unauthenticated, adjacent attacker to execute arbitrary code with administrative privileges or cause a denial of service (DoS) condition on an affected device. This vulnerability is due to insufficient input validation. An attacker could exploit this vulnerability by sending crafted Cisco UDLD protocol packets to a directly connected, affected device. A successful exploit could allow the attacker to execute arbitrary code with administrative privileges or cause the Cisco UDLD process to crash and restart multiple times, causing the affected device to reload and resulting in a DoS condition. Note: The UDLD feature is disabled by default, and the conditions to exploit this vulnerability are strict. The attacker needs full control of a directly connected device. That device must be connected over a port channel that has UDLD enabled. To trigger arbitrary code execution, both the UDLD-enabled port channel and specific system conditions must exist. In the absence of either the UDLD-enabled port channel or the system conditions, attempts to exploit this vulnerability will result in a DoS condition. It is possible, but highly unlikely, that an attacker could control the necessary conditions for exploitation. The CVSS score reflects this possibility. However, given the complexity of exploitation, Cisco has assigned a Medium Security Impact Rating (SIR) to this vulnerability.

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An arbitrary code execution or denial of service (DoS) vulnerability exists in Unidirectional Link Detection (UDLD) feature of Cisco NX-OS Software due to insufficient input validation. An unauthenticated, adjacent attacker can exploit this issue by sending crafted Cisco UDLD protocol packets to a directly connected, affected device, to cause the device to reload, resulting in a DoS condition or arbitrary code execution.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

An arbitrary code execution or denial of service (DoS) vulnerability exists in Unidirectional Link Detection (UDLD) feature of Cisco FXOS Software due to insufficient input validation. An unauthenticated, adjacent attacker can exploit this issue by sending crafted Cisco UDLD protocol packets to a directly connected, affected device, to cause the device to reload, resulting in a DoS condition or arbitrary code execution.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Severity
501235	Cisco FXOS and NX-OS Software Unidirectional Link Detection Denial of Service and Arbitrary Code Execution (CVE-2021-1368)	Tenable OT Security	Tenable.ot	high
149719	Cisco NX-OS Software Unidirectional Link Detection DoS / Code Execution (cisco-sa-nxos-udld-rce-xetH6w35)	Nessus	CISCO	high
149718	Cisco FXOS Software Unidirectional Link Detection DoS / Code Execution (cisco-sa-nxos-udld-rce-xetH6w35)	Nessus	CISCO	high

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CVE-2021-1368

high

Tenable Plugins

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high

high