cisco-sa-nxos-udld-rce-xetH6w35: Cisco FXOS and NX-OS Software Unidirectional Link Detection Denial of Service and Arbitrary Code Execution Vulnerability
First published: Wed Feb 24 2021(Updated: )
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. 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-nxos-udld-rce-xetH6w35
Credit: This vulnerability was found during the resolution a Cisco TAC support case
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Cisco FX-OS | =2.9<2.9.1.1351>=Earlier than 2.8<=2.8<2.8.1.1431 | 2.9.1.1351 2.8.1.1431 |
| 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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Reference Links
Frequently Asked Questions
What is the severity of cisco-sa-nxos-udld-rce-xetH6w35?
The severity of cisco-sa-nxos-udld-rce-xetH6w35 is high with a CVSS score of 8.8.
What is the vulnerability in Cisco FXOS and NX-OS Software?
The vulnerability in Cisco FXOS and NX-OS Software is in the Unidirectional Link Detection (UDLD) feature.
What can an attacker do with this vulnerability?
An unauthenticated, adjacent attacker can execute arbitrary code with administrative privileges or cause a denial of service (DoS) condition on an affected device.
Which versions of Cisco FXOS Software are affected by this vulnerability?
Versions 2.8 and 2.9 of Cisco FXOS Software are affected.
Which versions of Cisco UCS Software are affected by this vulnerability?
Versions 4.0 and 4.1 of Cisco UCS Software are affected.
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- canonical/cisco fx-os
- version/cisco fx-os/2.9
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