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Medium

Axios has a NO_PROXY Hostname Normalization Bypass that Leads to SSRF

  • Disclosed: 09.04.2026
  • Updated: 11.10.2026 10:22

Axios does not correctly handle hostname normalization when checking NO_PROXY rules. Requests to loopback addresses like localhost. (with a trailing dot) or [::1] (IPv6 literal) skip NO_PROXY matching and go through the configured proxy.

This goes against what developers expect and lets attackers force requests through a proxy, even if NO_PROXY is set up to protect loopback or internal services.

According to RFC 1034 §3.1 and RFC 3986 §3.2.2, a hostname can have a trailing dot to show it is a fully qualified domain name (FQDN). At the DNS level, localhost. is the same as localhost. However, Axios does a literal string comparison instead of normalizing hostnames before checking NO_PROXY. This causes requests like http://localhost.:8080/ and http://[::1]:8080/ to be incorrectly proxied.

This issue leads to the possibility of proxy bypass and SSRF vulnerabilities allowing attackers to reach sensitive loopback or internal services despite the configured protections.

PoC

js
import http from "http";
import axios from "axios";

const proxyPort = 5300;

http.createServer((req, res) => {
  console.log("[PROXY] Got:", req.method, req.url, "Host:", req.headers.host);
  res.writeHead(200, { "Content-Type": "text/plain" });
  res.end("proxied");
}).listen(proxyPort, () => console.log("Proxy", proxyPort));

process.env.HTTP_PROXY = `http://127.0.0.1:${proxyPort}`;
process.env.NO_PROXY = "localhost,127.0.0.1,::1";

async function test(url) {
  try {
    await axios.get(url, { timeout: 2000 });
  } catch {}
}

setTimeout(async () => {
  console.log("\n[*] Testing http://localhost.:8080/");
  await test("http://localhost.:8080/"); // goes through proxy

  console.log("\n[*] Testing http://[::1]:8080/");
  await test("http://[::1]:8080/"); // goes through proxy
}, 500);

Expected: Requests bypass the proxy (direct to loopback). Actual: Proxy logs requests for localhost. and [::1].

Impact

  • Applications that rely on NO_PROXY=localhost,127.0.0.1,::1 for protecting loopback/internal access are vulnerable.

  • Attackers controlling request URLs can:

    • Force Axios to send local traffic through an attacker-controlled proxy.
    • Bypass SSRF mitigations relying on NO_PROXY rules.
    • Potentially exfiltrate sensitive responses from internal services via the proxy.

Affected Versions

  • Confirmed on Axios 1.12.2 (latest at time of testing).
  • affects all versions that rely on Axios’ current NO_PROXY evaluation.

Remediation Axios should normalize hostnames before evaluating NO_PROXY, including:

  • Strip trailing dots from hostnames (per RFC 3986).
  • Normalize IPv6 literals by removing brackets for matching.

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
npm package axios >= 1.0.0, < 1.15.0, < 0.31.0 1.15.0, 0.31.0

References

CVSS score 4.8/10
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
Weakness (CWE)
CWE-441, CWE-918
Platform
npm
Package
axios
Disclosed
09.04.2026
Updated
11.10.2026 10:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-3p68-rc4w-qgx5 - 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: 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
  17. 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
  18. 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
  19. 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
  20. Axios has a NO_PROXY Hostname Normalization Bypass that Leads to SSRF this entry
    Medium · 4.8 CVE-2025-62718 >= 1.0.0, < 1.15.0, < 0.31.0 1.15.0, 0.31.0
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