Vulnerability Database

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Total vulnerabilities in the database

follow-redirects leaks Custom Authentication Headers to Cross-Domain Redirect Targets — follow-redirects / follow-redirects

Exposure of Sensitive Information to an Unauthorized Actor

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.

No technical information available.

CWEs:

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