CVE-2026-101907: Axios: maxRedirects: 0 is not enforced by the fetch adapter, allowing redirect-based SSRF

Axios exposes maxRedirects to limit redirect following, and maxRedirects: 0 is used by applications as a redirect-based SSRF guard. The Node HTTP adapter enforces this option. The fetch adapter does not read it and does not set a Fetch API redirect mode, so the runtime default of redirect: 'follow' applies.

Applications are affected when they rely on maxRedirects: 0 and use the fetch adapter, either explicitly or because the runtime selects it.

Axios 1.17.0 exposes maxRedirects as a configuration option to limit redirect following, and setting it to 0 is a documented pattern for preventing redirect-based SSRF. The HTTP adapter enforces this via follow-redirects. The fetch adapter does not read maxRedirects at all - it passes requests to the underlying fetch() call with no redirect option, which defaults to 'follow', so redirects are followed by the runtime rather than being constrained by axios maxRedirects.

In the attached PoC, a request issued with maxRedirects: 0 and adapter: 'fetch' follows a 302 redirect to an internal service and returns its response, while the same request with adapter: 'http' correctly throws. A second bypass case demonstrates that the redirect can reach a state-changing internal endpoint, not just read-only ones, proving both confidentiality and integrity impact.

This affects any application that sets maxRedirects: 0 as a redirect guard and runs in an environment where the fetch adapter is active: Deno, Bun, Cloudflare Workers, or Node.js with adapter: 'fetch' set explicitly.