Cisco

Security Advisory

High-Severity DoS Vulnerability in Cisco NX-OS Software

MPLS Encapsulated IPv6 Denial of Service Vulnerability

OEM CISCO 
Severity High 
CVSS score 7.4 
CVEs CVE-2025-20111 
Exploited in Wild No 
Patch/Remediation Available Yes 
Advisory Version 1.0 

Overview 

A high-severity vulnerability (CVE-2025-20111) in Cisco Nexus 3000 and 9000 Series Switches operating in standalone NX-OS mode could allow unauthenticated attackers to trigger a denial-of-service (DoS) condition by sending crafted ethernet frames, leading to unexpected device reloads. 

Vulnerability Name CVE ID Product Affected Severity 
 Denial of service vulnerability  CVE-2025-20111   Cisco Nexus   High 

Technical Summary 

The vulnerability originates from improper handling of specific Ethernet frames within the health monitoring diagnostics of Cisco Nexus switches.

An unauthenticated, adjacent attacker can exploit this flaw by sending a sustained rate of crafted Ethernet frames to a vulnerable device. Successful exploitation results in repeated device reloads, disrupting network operations and potentially impacting high-availability environments. 

CVE ID System Affected Vulnerability Details Impact 
 CVE-2025-20111  Nexus 3000 Series: 3100, 3200, 3400, and 3600 models Nexus 9000 Series: 9200, 9300, and 9400 switches running standalone NX-OS Improper handling of specific Ethernet frames in health monitoring diagnostics  Repeated device reboots, potential network downtime  

Remediation: 

  • Apply Software Updates: Cisco has released patched software versions to address the vulnerability. Network administrators should upgrade affected devices immediately. 
  • Use Cisco Software Checker: Organizations should verify their exposure using Cisco’s Software Checker tool to identify the earliest fixed release. 
  • Implement Workarounds: If immediate patching is not feasible, organizations can mitigate risks using Access Control Lists (ACLs) to filter anomalous Ethernet frames targeting the health monitoring subsystem. 

Conclusion: 

CVE-2025-20111 presents a significant risk to enterprise and data center networks relying on Cisco Nexus switches. While there is no known active exploitation, organizations should prioritize patching and mitigation strategies to prevent service disruptions. Proactive monitoring and adherence to Cisco’s security advisories will help ensure network resilience against potential exploitation. 

References: 

Security Advisory

Cisco Meeting Management to Prone to Attack Vectors; Vulnerability CVE-2025-20156 

Cisco has warned about a new privilege escalation vulnerability in its Meeting Management tool that could allow a remote attacker to gain administrator privileges on exposed instances.

The vulnerability, CVE-2025-20156  was disclosed by Cisco on January 22 and is awaiting further analysis by the US National Vulnerability Database (NVD)

OEM Cisco 
Severity Critical 
CVSS 9.9 
CVEs CVE-2025-20156 
Exploited in Wild No 
Patch/Remediation Available Yes 
Advisory Version 1.0 

Overview 

A critical vulnerability (CVE-2025-20156) in Cisco Meeting Management could allow attackers to gain unauthorized administrative access. This issue affects versions prior to 3.9.1 and has been classified as critical. Cisco strongly recommends updating to the latest fixed version to address this risk. 

Vulnerability Name CVE ID Product Affected Severity 
 Privilege Escalation Vulnerability  CVE-2025-20156  Cisco  Critical 

Technical Summary 

A critical security vulnerability has been identified in Cisco Meeting Management. This flaw resides in the REST API and stems from improper enforcement of authorization protocols for REST API users. Remote, authenticated attackers with low-level privileges can exploit this issue by sending specially crafted API requests to specific endpoints. A successful exploit could allow attackers to escalate their privileges to administrator level and gain control over edge nodes managed by Cisco Meeting Management. 

CVE ID System Affected Vulnerability Details Impact 
CVE-2025-20156  Cisco Meeting Management  prior to version 3.9.1 Insufficient authorization checks in the REST API allow attackers to send crafted API requests to escalate privileges.  Attackers can gain full administrative control and disrupt business operations.  

Remediation: 

  1. Update to the Latest Version: 
  • Upgrade Cisco Meeting Management to version 3.9.1or later. 
  1. Regular Security Practices: 
  • Monitor Cisco’s security advisories. 
  • Regularly update systems to address emerging threats. 

Conclusion: 

CVE-2025-20156 poses a critical risk to Cisco Meeting Management users. Exploiting this flaw could disrupt operations by granting attacker’s administrative control. Immediate updates are crucial to mitigate the risk and protect affected systems. 

References: 

  • https://cybersecuritynews.com/cisco-meeting-management-vulnerability/ 

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