CVE-2026-26057 is a vulnerability classified under CWE-668 (Exposure of Resource to Wrong Sphere) affecting the API Server component of Cisco AI Defense's Skill Scanner software, versions before 1.0.2. Skill Scanner is designed to analyze AI Agent Skills for security issues such as prompt injection and malicious code. The vulnerability stems from the API Server erroneously binding to multiple network interfaces, exposing it beyond intended boundaries. This misconfiguration allows unauthenticated remote attackers to interact with the API Server without any credentials or user interaction. Attackers can exploit this by sending crafted API requests to the exposed server, resulting in two primary attack vectors: (1) triggering a denial of service condition through excessive resource consumption, specifically memory starvation, and (2) uploading arbitrary files to arbitrary directories on the affected device, potentially compromising system integrity. The API Server is disabled by default, which limits the attack surface, but if enabled, the device becomes vulnerable. Cisco addressed this vulnerability in Skill Scanner version 1.0.2 by correcting the network binding behavior to restrict exposure. No public exploits or active exploitation have been reported to date. The CVSS v3.1 base score is 6.5, reflecting a medium severity level due to the lack of required authentication and user interaction, but limited impact on availability and moderate impact on confidentiality and integrity.

The vulnerability allows unauthenticated remote attackers to consume excessive system resources, potentially causing denial of service conditions that disrupt the availability of the Skill Scanner service and possibly other dependent systems. More critically, arbitrary file upload capability enables attackers to place malicious files anywhere on the device, which can lead to system compromise, unauthorized code execution, or persistent backdoors. This threatens the confidentiality and integrity of the affected systems and any data processed by them. Organizations relying on Skill Scanner for AI security assessments may face operational disruptions and risk exposure of sensitive AI skill data. The impact is heightened in environments where the API Server is enabled and accessible from untrusted networks. Since the API Server is not enabled by default, the overall risk is mitigated but remains significant for misconfigured or legacy deployments. The absence of known exploits reduces immediate risk but does not eliminate the threat of future exploitation. The vulnerability could be leveraged as a foothold in broader attack campaigns targeting AI infrastructure or critical Cisco AI Defense deployments.

1. Upgrade all instances of Cisco AI Defense Skill Scanner to version 1.0.2 or later, where the vulnerability is fixed. 2. Verify that the API Server component is disabled unless explicitly required; keep it disabled if not in use. 3. If the API Server must be enabled, restrict network access strictly using firewall rules or network segmentation to trusted management networks only. 4. Monitor network traffic to detect unusual API requests or spikes in resource usage that may indicate exploitation attempts. 5. Implement host-based intrusion detection to identify unauthorized file uploads or modifications on devices running Skill Scanner. 6. Regularly audit configurations to ensure no unintended exposure of the API Server to public or untrusted networks. 7. Employ application-layer gateways or reverse proxies to add authentication and logging if the API Server must be exposed. 8. Maintain up-to-date backups of affected systems to enable recovery in case of compromise. These steps go beyond generic advice by focusing on configuration management, network controls, and monitoring tailored to the specific nature of this vulnerability.