When applications rely on the fetch adapter, either through explicit configuration, environment-specific resolution (such as in Deno, Bun, or Cloudflare Workers), or automatic adapter selection, the library fails to pass a restrictive redirect mode to the underlying fetch() API. Consequently, the default runtime behavior of redirect: 'follow' takes precedence. This discrepancy allows attackers who can influence the initial request URL or provide a malicious redirecting server to bypass intended SSRF protections, leading to potential unauthorized access to internal resources or state-changing operations on internal endpoints reachable from the application environment.

Impact

Successful exploitation allows for redirect-based SSRF, which may lead to the exposure of sensitive internal data or unauthorized modification of internal system states. The impact is significant for applications operating in cloud or serverless environments where network perimeter defenses are often bypassed by internal requests. If an internal service processes state-changing requests without additional authentication, an attacker can trigger unauthorized mutations by providing an open redirect or a malicious redirection chain that directs the application to the internal target.

Recommendation

Detection and remediation should focus on identifying applications using the fetch adapter in security-sensitive contexts.

• Audit application code for usages of axios.get() or axios.request() that specify maxRedirects: 0 without explicit fetchOptions to define redirect behavior.
• Where the fetch adapter is required, enforce manual redirect handling by setting fetchOptions: { redirect: 'manual' } in the axios configuration.
• If the application environment supports it, prefer the Node.js HTTP adapter for requests requiring strict adherence to redirect limits.
• Implement network-level egress filtering to prevent the application server from initiating connections to sensitive internal service segments (127.0.0.1, 169.254.169.254, or private RFC1918 ranges) unless explicitly required.