A flaw in Nightingale 9.1.1 allows an attacker who can supply a URL to the http_fetch tool to bypass the SSRF guard by encoding a forbidden IPv4 address inside an IPv6 literal. The function only unpacks standard IPv4‑mapped addresses before validating against the banned ranges, but it fails to detect 6to4, NAT64, or deprecated site‑local prefixes. When this bypass succeeds, internal or metadata services (for example 169.254.169.254) become reachable from the AI‑agent, compromising confidentiality, integrity, and availability of internal services. The vulnerability maps to CWE‑918, indicating a request forging weakness that can be routed to internal resources.

The affected vendor is Nightingale (ccfos) and the product version is 9.1.1, as identified in the commit 8362cbe on the main branch. The vulnerability exists in the aiagent/tools/http.go source and affects any deployment that uses the http_fetch tool in Nightingale 9.1.1 or earlier releases containing this code path.

The CVSS score of 7.1 reflects high impact but moderate exploitation complexity; EPSS is not available and the vulnerability is not listed in CISA’s KEV catalog, implying no known active exploitation. The likely attack vector is an attacker able to influence the URL parameter for http_fetch, which may be achieved through privileged users, compromised applications, or exposed APIs. Successful exploitation exposes the internal network to arbitrary HTTP requests, potentially leaking sensitive data or enabling further lateral movement.