CVE-2003-0511 in IOS
Summary
by MITRE
The web server for Cisco Aironet AP1x00 Series Wireless devices running certain versions of IOS 12.2 allow remote attackers to cause a denial of service (reload) via a malformed URL.
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Analysis
by VulDB Data Team • 08/12/2025
The Cisco Aironet AP1x00 Series Wireless Access Points represent critical infrastructure components in wireless networking deployments, serving as fundamental building blocks for enterprise and corporate wireless connectivity. These devices operate with Cisco IOS 12.2 firmware versions that contain a significant vulnerability allowing remote attackers to trigger a denial of service condition through specifically crafted malformed URLs. This vulnerability exists within the web server implementation of the access point's operating system, which processes HTTP requests without proper input validation mechanisms. The affected devices are particularly concerning because they often serve as primary wireless access points in sensitive environments where continuous network availability is paramount for business operations and security monitoring activities.
The technical flaw manifests in the web server component's failure to properly validate URL parameters when processing incoming HTTP requests. When a remote attacker crafts a malformed URL containing specially constructed characters or sequences, the web server processes this input without adequate sanitization or bounds checking. This processing error leads to a buffer overflow condition or other memory corruption issues within the web server's execution context, ultimately causing the device to crash and automatically reload its operating system. The vulnerability specifically targets the HTTP server functionality that handles web-based management interfaces, which are commonly used for configuration and monitoring purposes by network administrators. The flaw demonstrates poor input validation practices that align with CWE-121, which addresses buffer overflow conditions, and CWE-20, which covers input validation issues that can lead to various security vulnerabilities.
The operational impact of this vulnerability extends beyond simple service disruption, as it can compromise network availability and potentially provide attackers with opportunities for further exploitation. When an access point reloads due to this vulnerability, it temporarily removes wireless connectivity for all devices associated with that access point, which can result in significant business disruption depending on the network topology and the criticality of the affected services. The remote nature of the attack means that adversaries can exploit this vulnerability from outside the network perimeter, making it particularly dangerous for wireless networks that are exposed to external threats. Network administrators may experience unexpected downtime and service interruptions, while the device's automatic reload process can cause temporary loss of network visibility and monitoring capabilities. This vulnerability also creates opportunities for attackers to perform persistent denial of service attacks by repeatedly exploiting the flaw, potentially causing extended network outages that can affect business operations and security incident response capabilities.
Mitigation strategies for this vulnerability should include immediate firmware updates from Cisco to address the specific web server implementation flaws. Network administrators should also implement network segmentation and access control measures to limit exposure of these devices to untrusted networks, particularly by placing them behind firewalls or network access control lists that restrict HTTP traffic. Additional protective measures include monitoring network traffic for suspicious URL patterns that may indicate exploitation attempts, implementing intrusion detection systems that can identify malformed HTTP requests, and establishing automated alerting mechanisms for device reload events. The vulnerability's characteristics align with ATT&CK technique T1499.001, which covers network denial of service attacks, and organizations should consider implementing defensive measures such as rate limiting for HTTP requests and regular security assessments of wireless network infrastructure. Regular patch management programs should be established to ensure that all Cisco wireless access points receive timely security updates, and network documentation should be maintained to track vulnerable device deployments across the organization's infrastructure.