A vulnerability in the Central Web Authentication (CWA) feature of Cisco IOS XE Software for Wireless Controllers could allow an unauthenticated, adjacent attacker to bypass the pre-authentication access control list (ACL), which could allow access to network resources before user authentication.
This vulnerability is due to a logic error when activating the pre-authentication ACL that is received from the authentication, authorization, and accounting (AAA) server. An attacker could exploit this vulnerability by connecting to a wireless network that is configured for CWA and sending traffic through an affected device that should be denied by the configured ACL before user authentication. A successful exploit could allow the attacker to bypass configured ACL protections on the affected device before the user authentication is completed, allowing the attacker to access trusted networks that the device might be protecting.
| Software | From | Fixed in |
|---|---|---|
| cisco / ios_xe | 16.6.1 | 16.6.1.x |
| cisco / ios_xe | 16.4.1 | 16.4.1.x |
| cisco / ios_xe | 16.3.1 | 16.3.1.x |
| cisco / ios_xe | 16.3.1a | 16.3.1a.x |
| cisco / ios_xe | 16.3.2 | 16.3.2.x |
| cisco / ios_xe | 16.3.3 | 16.3.3.x |
| cisco / ios_xe | 16.9.1 | 16.9.1.x |
| cisco / ios_xe | 16.8.1 | 16.8.1.x |
| cisco / ios_xe | 16.7.1 | 16.7.1.x |
| cisco / ios_xe | 16.6.3 | 16.6.3.x |
| cisco / ios_xe | 16.6.2 | 16.6.2.x |
| cisco / ios_xe | 16.5.1b | 16.5.1b.x |
| cisco / ios_xe | 16.5.1a | 16.5.1a.x |
| cisco / ios_xe | 16.5.1 | 16.5.1.x |
| cisco / ios_xe | 16.4.2 | 16.4.2.x |
| cisco / ios_xe | 16.3.6 | 16.3.6.x |
| cisco / ios_xe | 16.3.5b | 16.3.5b.x |
| cisco / ios_xe | 16.3.4 | 16.3.4.x |
| cisco / ios_xe | 16.10.1 | 16.10.1.x |
| cisco / ios_xe | 16.9.1s | 16.9.1s.x |
| cisco / ios_xe | 16.9.1b | 16.9.1b.x |
| cisco / ios_xe | 16.9.1a | 16.9.1a.x |
| cisco / ios_xe | 16.9.2 | 16.9.2.x |
| cisco / ios_xe | 16.8.1e | 16.8.1e.x |
| cisco / ios_xe | 16.8.2 | 16.8.2.x |
| cisco / ios_xe | 16.8.1d | 16.8.1d.x |
| cisco / ios_xe | 16.8.1c | 16.8.1c.x |
| cisco / ios_xe | 16.8.1s | 16.8.1s.x |
| cisco / ios_xe | 16.8.1b | 16.8.1b.x |
| cisco / ios_xe | 16.8.1a | 16.8.1a.x |
| cisco / ios_xe | 16.7.4 | 16.7.4.x |
| cisco / ios_xe | 16.7.3 | 16.7.3.x |
| cisco / ios_xe | 16.7.2 | 16.7.2.x |
| cisco / ios_xe | 16.7.1b | 16.7.1b.x |
| cisco / ios_xe | 16.7.1a | 16.7.1a.x |
| cisco / ios_xe | 16.6.4 | 16.6.4.x |
| cisco / ios_xe | 16.5.3 | 16.5.3.x |
| cisco / ios_xe | 16.5.2 | 16.5.2.x |
| cisco / ios_xe | 16.4.3 | 16.4.3.x |
| cisco / ios_xe | 16.3.8 | 16.3.8.x |
| cisco / ios_xe | 16.3.7 | 16.3.7.x |
| cisco / ios_xe | 16.3.5 | 16.3.5.x |
| cisco / ios_xe | 17.4.1 | 17.4.1.x |
| cisco / ios_xe | 17.2.1 | 17.2.1.x |
| cisco / ios_xe | 17.1.1s | 17.1.1s.x |
| cisco / ios_xe | 17.1.1a | 17.1.1a.x |
| cisco / ios_xe | 17.1.1 | 17.1.1.x |
| cisco / ios_xe | 16.12.4 | 16.12.4.x |
| cisco / ios_xe | 16.12.1t | 16.12.1t.x |
| cisco / ios_xe | 16.12.1x | 16.12.1x.x |
| cisco / ios_xe | 16.12.8 | 16.12.8.x |
| cisco / ios_xe | 16.12.3 | 16.12.3.x |
| cisco / ios_xe | 16.12.2a | 16.12.2a.x |
| cisco / ios_xe | 16.12.1y | 16.12.1y.x |
| cisco / ios_xe | 16.12.2 | 16.12.2.x |
| cisco / ios_xe | 16.12.1w | 16.12.1w.x |
| cisco / ios_xe | 16.12.1c | 16.12.1c.x |
| cisco / ios_xe | 16.12.1a | 16.12.1a.x |
| cisco / ios_xe | 16.12.1s | 16.12.1s.x |
| cisco / ios_xe | 16.12.1 | 16.12.1.x |
| cisco / ios_xe | 16.11.1s | 16.11.1s.x |
| cisco / ios_xe | 16.11.2 | 16.11.2.x |
| cisco / ios_xe | 16.11.1b | 16.11.1b.x |
| cisco / ios_xe | 16.11.1a | 16.11.1a.x |
| cisco / ios_xe | 16.11.1 | 16.11.1.x |
| cisco / ios_xe | 16.10.3 | 16.10.3.x |
| cisco / ios_xe | 16.10.1g | 16.10.1g.x |
| cisco / ios_xe | 16.10.1f | 16.10.1f.x |
| cisco / ios_xe | 16.10.2 | 16.10.2.x |
| cisco / ios_xe | 16.10.1d | 16.10.1d.x |
| cisco / ios_xe | 16.10.1e | 16.10.1e.x |
| cisco / ios_xe | 16.10.1c | 16.10.1c.x |
| cisco / ios_xe | 16.10.1s | 16.10.1s.x |
| cisco / ios_xe | 16.10.1b | 16.10.1b.x |
| cisco / ios_xe | 16.10.1a | 16.10.1a.x |
| cisco / ios_xe | 16.9.5f | 16.9.5f.x |
| cisco / ios_xe | 16.9.5 | 16.9.5.x |
| cisco / ios_xe | 16.9.3a | 16.9.3a.x |
| cisco / ios_xe | 16.9.4 | 16.9.4.x |
| cisco / ios_xe | 16.9.3 | 16.9.3.x |
| cisco / ios_xe | 16.8.3 | 16.8.3.x |
| cisco / ios_xe | 16.6.9 | 16.6.9.x |
| cisco / ios_xe | 16.6.8 | 16.6.8.x |
| cisco / ios_xe | 16.6.7 | 16.6.7.x |
| cisco / ios_xe | 16.6.6 | 16.6.6.x |
| cisco / ios_xe | 16.6.5a | 16.6.5a.x |
| cisco / ios_xe | 16.6.4a | 16.6.4a.x |
| cisco / ios_xe | 16.6.5 | 16.6.5.x |
| cisco / ios_xe | 16.3.10 | 16.3.10.x |
| cisco / ios_xe | 16.3.9 | 16.3.9.x |
| cisco / ios_xe | 17.11.99sw | 17.11.99sw.x |
| cisco / ios_xe | 17.13.1a | 17.13.1a.x |
| cisco / ios_xe | 17.13.1 | 17.13.1.x |
| cisco / ios_xe | 17.12.1y | 17.12.1y.x |
| cisco / ios_xe | 17.12.2a | 17.12.2a.x |
| cisco / ios_xe | 17.12.3 | 17.12.3.x |
| cisco / ios_xe | 17.12.2 | 17.12.2.x |
| cisco / ios_xe | 17.12.1x | 17.12.1x.x |
| cisco / ios_xe | 17.12.1a | 17.12.1a.x |
| cisco / ios_xe | 17.12.1w | 17.12.1w.x |
| cisco / ios_xe | 17.12.1 | 17.12.1.x |
| cisco / ios_xe | 17.11.1a | 17.11.1a.x |
| cisco / ios_xe | 17.11.1 | 17.11.1.x |
| cisco / ios_xe | 17.9.5b | 17.9.5b.x |
| cisco / ios_xe | 17.9.5a | 17.9.5a.x |
| cisco / ios_xe | 17.9.1y1 | 17.9.1y1.x |
| cisco / ios_xe | 17.9.3a | 17.9.3a.x |
| cisco / ios_xe | 17.9.1x1 | 17.9.1x1.x |
| cisco / ios_xe | 17.9.2a | 17.9.2a.x |
| cisco / ios_xe | 17.9.3 | 17.9.3.x |
| cisco / ios_xe | 17.9.1y | 17.9.1y.x |
| cisco / ios_xe | 17.9.1x | 17.9.1x.x |
| cisco / ios_xe | 17.9.1a | 17.9.1a.x |
| cisco / ios_xe | 17.9.2 | 17.9.2.x |
| cisco / ios_xe | 17.9.1w | 17.9.1w.x |
| cisco / ios_xe | 17.9.1 | 17.9.1.x |
| cisco / ios_xe | 17.8.1a | 17.8.1a.x |
| cisco / ios_xe | 17.8.1 | 17.8.1.x |
| cisco / ios_xe | 17.10.1b | 17.10.1b.x |
| cisco / ios_xe | 17.10.1a | 17.10.1a.x |
| cisco / ios_xe | 17.10.1 | 17.10.1.x |
| cisco / ios_xe | 17.7.2 | 17.7.2.x |
| cisco / ios_xe | 17.7.1b | 17.7.1b.x |
| cisco / ios_xe | 17.7.1a | 17.7.1a.x |
| cisco / ios_xe | 17.7.1 | 17.7.1.x |
| cisco / ios_xe | 17.6.5a | 17.6.5a.x |
| cisco / ios_xe | 17.6.5 | 17.6.5.x |
| cisco / ios_xe | 17.6.1z1 | 17.6.1z1.x |
| cisco / ios_xe | 17.6.4 | 17.6.4.x |
| cisco / ios_xe | 17.6.3a | 17.6.3a.x |
| cisco / ios_xe | 17.6.1z | 17.6.1z.x |
| cisco / ios_xe | 17.6.1y | 17.6.1y.x |
| cisco / ios_xe | 17.6.3 | 17.6.3.x |
| cisco / ios_xe | 17.6.1x | 17.6.1x.x |
| cisco / ios_xe | 17.6.1a | 17.6.1a.x |
| cisco / ios_xe | 17.6.1w | 17.6.1w.x |
| cisco / ios_xe | 17.6.2 | 17.6.2.x |
| cisco / ios_xe | 17.6.1 | 17.6.1.x |
| cisco / ios_xe | 17.5.1a | 17.5.1a.x |
| cisco / ios_xe | 17.5.1 | 17.5.1.x |
| cisco / ios_xe | 17.4.2a | 17.4.2a.x |
| cisco / ios_xe | 17.4.1b | 17.4.1b.x |
| cisco / ios_xe | 17.4.1a | 17.4.1a.x |
| cisco / ios_xe | 17.4.2 | 17.4.2.x |
| cisco / ios_xe | 17.3.7 | 17.3.7.x |
| cisco / ios_xe | 17.3.5b | 17.3.5b.x |
| cisco / ios_xe | 17.3.5a | 17.3.5a.x |
| cisco / ios_xe | 17.3.4c | 17.3.4c.x |
| cisco / ios_xe | 17.3.4b | 17.3.4b.x |
| cisco / ios_xe | 17.3.6 | 17.3.6.x |
| cisco / ios_xe | 17.3.4a | 17.3.4a.x |
| cisco / ios_xe | 17.3.5 | 17.3.5.x |
| cisco / ios_xe | 17.3.4 | 17.3.4.x |
| cisco / ios_xe | 17.3.1z | 17.3.1z.x |
| cisco / ios_xe | 17.3.1x | 17.3.1x.x |
| cisco / ios_xe | 17.3.2a | 17.3.2a.x |
| cisco / ios_xe | 17.3.1w | 17.3.1w.x |
| cisco / ios_xe | 17.3.1a | 17.3.1a.x |
| cisco / ios_xe | 17.3.3 | 17.3.3.x |
| cisco / ios_xe | 17.3.2 | 17.3.2.x |
| cisco / ios_xe | 17.3.1 | 17.3.1.x |
| cisco / ios_xe | 17.2.3 | 17.2.3.x |
| cisco / ios_xe | 17.2.2 | 17.2.2.x |
| cisco / ios_xe | 17.2.1v | 17.2.1v.x |
| cisco / ios_xe | 17.2.1a | 17.2.1a.x |
| cisco / ios_xe | 17.2.1r | 17.2.1r.x |
| cisco / ios_xe | 17.1.3 | 17.1.3.x |
| cisco / ios_xe | 17.1.1t | 17.1.1t.x |
| cisco / ios_xe | 16.12.9 | 16.12.9.x |
| cisco / ios_xe | 16.12.7 | 16.12.7.x |
| cisco / ios_xe | 16.12.6a | 16.12.6a.x |
| cisco / ios_xe | 16.12.1z2 | 16.12.1z2.x |
| cisco / ios_xe | 16.12.5b | 16.12.5b.x |
| cisco / ios_xe | 16.12.5a | 16.12.5a.x |
| cisco / ios_xe | 16.12.1z1 | 16.12.1z1.x |
| cisco / ios_xe | 16.12.6 | 16.12.6.x |
| cisco / ios_xe | 16.12.5 | 16.12.5.x |
| cisco / ios_xe | 16.12.4a | 16.12.4a.x |
| cisco / ios_xe | 16.12.3a | 16.12.3a.x |
| cisco / ios_xe | 16.12.3s | 16.12.3s.x |
| cisco / ios_xe | 16.12.2s | 16.12.2s.x |
| cisco / ios_xe | 16.9.8 | 16.9.8.x |
| cisco / ios_xe | 16.9.7 | 16.9.7.x |
| cisco / ios_xe | 16.9.6 | 16.9.6.x |
| cisco / ios_xe | 16.6.10 | 16.6.10.x |
| cisco / ios_xe | 16.3.11 | 16.3.11.x |
| cisco / ios_xe | 17.9.4a | 17.9.4a.x |
| cisco / ios_xe | 17.9.5 | 17.9.5.x |
| cisco / ios_xe | 17.9.4 | 17.9.4.x |
| cisco / ios_xe | 17.6.7 | 17.6.7.x |
| cisco / ios_xe | 17.6.6a | 17.6.6a.x |
| cisco / ios_xe | 17.6.6 | 17.6.6.x |
| cisco / ios_xe | 17.3.8a | 17.3.8a.x |
| cisco / ios_xe | 17.3.8 | 17.3.8.x |
| cisco / ios_xe | 16.12.11 | 16.12.11.x |
| cisco / ios_xe | 16.12.10a | 16.12.10a.x |
| cisco / ios_xe | 16.12.10 | 16.12.10.x |
A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.
A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.
Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.
Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.
SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.