CVE-2026-85692 in Nightingale
Summary
by MITRE • 09/04/2026
Nightingale (n9e), as of commit 8362cbe (main branch, confirmed 2026-08-27), contains a server-side request forgery vulnerability in the isPublicIP function in aiagent/tools/http.go, the SSRF guard for the http_fetch AI-agent tool. The function only unwraps standard IPv4-mapped (::ffff:a.b.c.d) IPv6 addresses before checking them against the forbidden-range list, and does not classify 6to4 (2002::/16), NAT64 (64:ff9b::/96, 64:ff9b:1::/48), or deprecated site-local (fec0::/10) addresses. On a dual-stack or NAT64-enabled host, an attacker able to supply a URL to the http_fetch tool can bypass the guard by encoding a forbidden IPv4 address (such as the cloud instance-metadata endpoint 169.254.169.254) in one of these IPv6 forms to reach internal or metadata services.
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Analysis
by VulDB Data Team • 09/04/2026
The vulnerability identified in Nightingale, specifically within the aiagent/tools/http.go module and affecting the isPublicIP function as of commit 8362cbe on the main branch, represents a critical server-side request forgery flaw rooted in incomplete input validation logic. The core technical deficiency lies in how the application handles IP address normalization prior to security checks. While the code correctly unwraps standard IPv4-mapped IPv6 addresses formatted as ::ffff:a.b.c.d and validates them against a list of forbidden ranges, it fails to account for other legacy or transitional IPv6 addressing schemes that can encode private or reserved IPv4 addresses. Specifically, the implementation does not classify 6to4 addresses within the 2002::/16 prefix range, NAT64 prefixes such as 64:ff9b::/96 and 64:ff9b:1::/48, nor deprecated site-local addresses in the fec0::/10 block. This oversight creates a significant blind spot in the SSRF guard mechanism designed to protect the http_fetch AI-agent tool from accessing internal resources.
From an operational perspective, this flaw allows an attacker who has the ability to supply URLs to the http_fetch function to bypass network-level restrictions by encoding forbidden IPv4 addresses into one of these unhandled IPv6 formats. For instance, a sensitive target such as the cloud instance-metadata endpoint at 169.254.169.254 can be represented in NAT64 format or other transitional address types that pass through the validation logic unchecked. On systems operating with dual-stack networking capabilities or those utilizing NAT64 for IPv6-to-IPv4 translation, these encoded addresses will resolve to their underlying private IPv4 counterparts during DNS resolution or network routing. Consequently, requests intended to be restricted from reaching internal services are successfully delivered to local infrastructure components that should remain inaccessible from external contexts.
The impact of this vulnerability is severe, particularly in cloud-native environments where instance metadata services provide critical authentication credentials and configuration data. By exploiting the SSRF bypass, an attacker can potentially exfiltrate sensitive information such as access keys, security tokens, or internal network topology details without triggering alarms associated with direct IPv4 requests to reserved ranges. This aligns directly with CWE-918, which describes Server-Side Request Forgery (SSRF) flaws where the server makes requests that appear legitimate but are manipulated by an attacker to target internal resources. Furthermore, this attack vector maps to MITRE ATT&CK technique T1502.003, known as Use Alternative Protocol Encoding for SSRF, which involves using non-standard or alternative protocol representations to evade security controls designed to block specific IP ranges or domains.
Mitigation requires a comprehensive overhaul of the IP validation logic within the isPublicIP function and related network handling components. Developers must implement robust normalization routines that detect and decode all forms of IPv4-mapped addresses, including 6to4, NAT64, and site-local prefixes, ensuring they are converted to their standard IPv4 representation before being checked against forbidden ranges. Additionally, integrating a well-tested IP address parsing library can help avoid manual implementation errors common in custom validation logic. It is also advisable to enforce strict allow-listing of permitted destination IPs or domains rather than relying solely on deny lists, as this approach reduces the attack surface associated with unhandled edge cases in protocol encoding. Regular security audits and static analysis tools configured to detect SSRF patterns should be employed to identify similar vulnerabilities across other parts of the application that handle external network requests.