Axios is a promise based HTTP client for the browser and Node.js. Prior to 1.15.1 and 0.31.1, he fix for no_proxy hostname normalization bypass is incomplete. When no_proxy=localhost is set, requests to 127.0.0.1 and [::1] still route through the proxy instead of bypassing it. The shouldBypassProxy() function does pure string matching — it does not resolve IP aliases or loopback equivalents. This vulnerability is fixed in 1.15.1 and 0.31.1.