CVE-2025-20111 is a high-severity vulnerability identified in the health monitoring diagnostics of Cisco Nexus 3000 Series Switches and Cisco Nexus 9000 Series Switches operating in standalone NX-OS mode. This vulnerability can lead to a denial of service (DoS) condition, posing significant risks to network stability and security.
Overview of CVE-2025-20111
Description
- Vulnerability: CVE-2025-20111 is a vulnerability in the health monitoring diagnostics of Cisco Nexus 3000 and 9000 Series Switches. It allows an unauthenticated, adjacent attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability arises from the incorrect handling of specific Ethernet frames.
- Impact: The vulnerability affects Cisco Nexus 3000 and 9000 Series Switches running standalone NX-OS mode. Exploiting this vulnerability can disrupt network operations by causing the affected devices to reload.
Technical Mechanics
Exploitation
- Attack Vector: The vulnerability can be exploited by remote attackers without requiring authentication. Attackers can send a sustained rate of crafted Ethernet frames to the affected device, triggering the vulnerability and causing the device to reload.
- Conditions for Exploitation: Successful exploitation requires the attacker to be on the same network segment as the target device, as the attack vector is adjacent network-based.
CVSS Score
The Common Vulnerability Scoring System (CVSS) provides a numerical score reflecting the severity of a vulnerability. The CVSS score for CVE-2025-20111 is as follows:
- CVSS v3.1 Base Score: 7.4 (High)
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
- Explanation:
- Attack Vector (AV): Adjacent Network (A) – The vulnerability is exploitable from an adjacent network.
- Attack Complexity (AC): Low (L) – The attack does not require special conditions.
- Privileges Required (PR): None (N) – No privileges are required to exploit the vulnerability.
- User Interaction (UI): None (N) – No user interaction is required.
- Scope (S): Changed (C) – The vulnerability affects resources beyond the vulnerable component.
- Confidentiality (C): None (N) – The vulnerability does not affect confidentiality.
- Integrity (I): None (N) – The vulnerability does not affect data integrity.
- Availability (A): High (H) – The vulnerability can lead to significant disruption of service.
Mitigation Measures
Immediate Actions
- Patch Management: Cisco has released software updates that address this vulnerability. Users of affected Cisco Nexus switches should apply these updates promptly to mitigate the risk.
- Workarounds: Cisco has provided workarounds that can help mitigate the vulnerability. These workarounds include configuring access control lists (ACLs) to block crafted Ethernet frames.
Long-Term Strategies
- Regular Security Audits: Conduct regular security audits and vulnerability assessments to identify and address potential weaknesses in the network infrastructure. These proactive measures help maintain a secure environment.
- Network Segmentation: Implement network segmentation to limit the spread of attacks within the network and isolate critical systems. This strategy ensures that even if one segment is compromised, the impact is contained.
- Behavioral Analysis: Deploy behavioral analysis tools to monitor for unusual network traffic patterns that may indicate an attack. These tools provide real-time insights and enable swift incident response.
- Incident Response Planning: Develop and maintain a comprehensive incident response plan to quickly and effectively respond to security incidents. Regular testing and updating of the plan ensure preparedness and resilience against potential threats.
Conclusion
CVE-2025-20111 is a high-severity vulnerability that poses significant risks to organizations using Cisco Nexus 3000 and 9000 Series Switches. By understanding the nature of this vulnerability and implementing the recommended mitigation measures, organizations can better protect their network infrastructure from potential exploitation. Vigilance and proactive security measures are essential for safeguarding against such vulnerabilities.
