CVE-2011-0963: The default configuration of the RADIUS authentication feature on the Cisco Network Admission Control (NAC)...

Security readout for executives and security teams

Cisco NAC Guest Server versions before 2.0.3 had a default RADIUS authentication configuration weakness. A remote attacker could bypass intended guest access controls and gain network connectivity. The sources do not describe the exact technique, affected deployment details, or exploitation in the wild. Exposure is limited to organizations still running Cisco NAC Guest Server software before 2.0.3 with the affected RADIUS authentication feature enabled or default-configured. Prioritize this if Cisco NAC Guest Server still controls guest or contractor network access. The vulnerability can undermine admission control, but urgency depends on whether the legacy product remains deployed. Mitigation focus: Identify any Cisco NAC Guest Server deployments and software versions.; Upgrade affected systems to Cisco NAC Guest Server 2.0.3 if applicable.; Review Cisco advisory guidance for configuration-specific mitigations or caveats..

Prepared

Jun 24, 2026, 13:28 UTC (UTC+00:00)

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.