Cisco: New Cisco Network Vulnerability Let Remote Attacker Cause DoS Attack

Cisco Patches High-Severity DoS Vulnerability in Network Management Tools

Cisco has disclosed a critical vulnerability (CVE-2026-20188, CVSS 7.5) affecting its Crosswork Network Controller (CNC) and Network Services Orchestrator (NSO), which could allow unauthenticated, remote attackers to trigger a Denial-of-Service (DoS) condition.

The flaw stems from uncontrolled resource consumption (CWE-400), where affected systems fail to enforce rate-limiting on incoming connections. Attackers can exploit this by flooding a server with excessive requests, exhausting available resources and rendering the system unresponsive. Recovery requires a manual reboot, disrupting network operations and locking out administrators.

Affected Versions & Fixes

• Cisco Crosswork Network Controller (CNC):
  • Vulnerable: Version 7.1 and earlier
  • Fixed: Version 7.2 (unaffected)
• Cisco Network Services Orchestrator (NSO):
  • Vulnerable: Versions 6.3 and earlier, 6.4 (up to 6.4.1.2)
  • Fixed: 6.4.1.3 and later; 6.5+ (unaffected)

Cisco discovered the issue internally (Bug ID CSCwr08237) while resolving a support case. While no active exploitation or public PoC exploits have been observed, the company warns that no workarounds exist upgrading to patched versions is the only mitigation.

Organizations using vulnerable deployments are advised to apply updates immediately to prevent potential service disruptions.

Source: https://cybersecuritynews.com/cisco-network-vulnerability-dos-attack/

Cisco cybersecurity rating report: https://www.rankiteo.com/company/cisco

"id": "CIS1778171136",
"linkid": "cisco",
"type": "Vulnerability",
"date": "1/2026",
"severity": "60",
"impact": "2",
"explanation": "Attack limited on finance or reputation"

{'affected_entities': [{'industry': 'Technology/Networking',
                        'name': 'Cisco',
                        'type': 'Corporation'}],
 'attack_vector': 'Remote',
 'description': 'Cisco has disclosed a critical vulnerability (CVE-2026-20188, '
                'CVSS 7.5) affecting its Crosswork Network Controller (CNC) '
                'and Network Services Orchestrator (NSO), which could allow '
                'unauthenticated, remote attackers to trigger a '
                'Denial-of-Service (DoS) condition. The flaw stems from '
                'uncontrolled resource consumption (CWE-400), where affected '
                'systems fail to enforce rate-limiting on incoming '
                'connections. Attackers can exploit this by flooding a server '
                'with excessive requests, exhausting available resources and '
                'rendering the system unresponsive. Recovery requires a manual '
                'reboot, disrupting network operations and locking out '
                'administrators.',
 'impact': {'downtime': 'Requires manual reboot',
            'operational_impact': 'Network operations disruption, '
                                  'administrator lockout',
            'systems_affected': 'Crosswork Network Controller (CNC), Network '
                                'Services Orchestrator (NSO)'},
 'investigation_status': 'Resolved (patch available)',
 'post_incident_analysis': {'corrective_actions': 'Internal discovery (Bug ID '
                                                  'CSCwr08237), patch release '
                                                  'for affected versions',
                            'root_causes': 'Uncontrolled resource consumption '
                                           '(CWE-400) due to lack of '
                                           'rate-limiting on incoming '
                                           'connections'},
 'recommendations': 'Organizations using vulnerable deployments are advised to '
                    'apply updates immediately to prevent potential service '
                    'disruptions.',
 'references': [{'source': 'Cisco Security Advisory'}],
 'response': {'containment_measures': 'Upgrade to patched versions (CNC 7.2, '
                                      'NSO 6.4.1.3 or later)',
              'recovery_measures': 'Manual reboot of affected systems',
              'remediation_measures': 'Apply security updates'},
 'title': 'Cisco Patches High-Severity DoS Vulnerability in Network Management '
          'Tools',
 'type': 'Denial-of-Service (DoS)',
 'vulnerability_exploited': 'CVE-2026-20188 (Uncontrolled Resource Consumption '
                            '- CWE-400)'}